倉(cāng)儲(chǔ)與配送管理練習(xí)題答案 職業(yè)技能實(shí)訓(xùn)一物流管理專(zhuān)業(yè)倉(cāng)儲(chǔ)與配送管理練習(xí)題答案1. 關(guān)于揀貨單位，下列說(shuō)法錯(cuò)誤的是（）答：一種貨物只能一種揀貨單位2. 下列關(guān)于分揀的四個(gè)選項(xiàng)錯(cuò)誤的是（）答：分揀過(guò)程不需要對(duì)貨物進(jìn)行分類(lèi)3. 揀貸的最小單位（）答：包裝的單件商品4. （ ）是配送的主體活動(dòng)答：送貨與分揀5. 配送中心作業(yè)貨物的特點(diǎn)是（）答：品種多、批量小6. 以銷(xiāo)售、經(jīng)營(yíng)為目的，以配送為手段的配送中心，叫做（）答：銷(xiāo)售配送中心7. 分貨方式一般有人工分貸和（ ）兩種答：自動(dòng)分貨8. 按照雙方約定的時(shí)間準(zhǔn)時(shí)將貸物配送到用戶的服務(wù)方式，叫做（）答：準(zhǔn)時(shí)配送9. 貨物在貸位上，揀貸員將每個(gè)客戶的貸物從貸位上取走的揀貸方式是（）答：摘果式揀取10. 為使揀貸員有效進(jìn)行作業(yè)，必須首先將（）答：原始傳票轉(zhuǎn)換成揀貨單11. 常用的方法有商品條碼檢查法、聲音輸入檢查法和（）答：重量計(jì)算檢查法12. 確定加工產(chǎn)品的數(shù)量、質(zhì)量、規(guī)格、包裝要求等，屬于流通加工管理中的（）答：計(jì)劃管理13. 標(biāo)明車(chē)號(hào)、駕駛員、送貨地點(diǎn)、客戶名稱等內(nèi)容的，屬于單據(jù)中的（）答：駕駛記錄表14. 作業(yè)員報(bào)出商品名稱、代碼和數(shù)量后，計(jì)算機(jī)接收后并自動(dòng)辨識(shí)，轉(zhuǎn)換成資料信息與發(fā)貸單進(jìn)行對(duì)答：聲音輸入檢查法15. 把每天劃分為幾個(gè)時(shí)點(diǎn)，補(bǔ)貸人員在時(shí)段內(nèi)檢查動(dòng)管揀貸架上的貸品存量，發(fā)現(xiàn)不足則及時(shí)補(bǔ)貨的補(bǔ)貨方式是（）答：定時(shí)補(bǔ)貨16. 檢查時(shí)用條碼掃描器閱讀條碼內(nèi)容，計(jì)算機(jī)再自動(dòng)把掃描信息與發(fā)貸單對(duì)比，從而檢查商品是否有誤的是（）答：商品條碼檢查法17. 分揀作業(yè)的時(shí)間消耗過(guò)程為（）。1訂單輸入階段2貸物分類(lèi)集中階段3人員行走和搬運(yùn)貸物階段4確認(rèn)貨物儲(chǔ)位揀取貨物階段答：134218. （）是一個(gè)網(wǎng)絡(luò)結(jié)構(gòu)系統(tǒng)，是由物流節(jié)點(diǎn)活動(dòng)和線路活動(dòng)構(gòu)成的答：配送系統(tǒng)19. 為使產(chǎn)品的使用價(jià)值得到保護(hù)，采取穩(wěn)固、改裝、冷凍、保鮮等手段，屬于（）的流通加工類(lèi)型。答：保護(hù)產(chǎn)品20. 平板玻璃、鋁材進(jìn)行裁減、切斷、彎曲、打眼，屬于（）的流通加工方式答：生產(chǎn)資料21. 自動(dòng)化立體倉(cāng)庫(kù)出入庫(kù)調(diào)度規(guī)則是（ ）答：出庫(kù)優(yōu)先22. 批量揀取的主要適用范圍為（）答：采購(gòu)產(chǎn)品品種共性大的訂單23. 偏重于維持較穩(wěn)定的作業(yè)效率，但在處理速度上慢于定時(shí)分批的方式是（）答：固定訂單量分批24. 配送中民經(jīng)理負(fù)責(zé)所有的活動(dòng)。下級(jí)對(duì)上級(jí)負(fù)責(zé)，上級(jí)的工作內(nèi)容是指揮、監(jiān)督下級(jí)。此配送中心答：金字塔型25. 配送中心的業(yè)務(wù)活動(dòng)是以（）發(fā)出的訂貸信息作為驅(qū)動(dòng)源。答：客戶訂單26. 分區(qū)的原則通常按商品銷(xiāo)售的（）答：按揀貨方式分區(qū)27. 對(duì)于燃料、水泥這些貸物的裝卸搬運(yùn)，配送中心通常采用（）作業(yè)方式。答：散裝作業(yè)法28. 下列有關(guān)配送的定義理解錯(cuò)誤的是（）。答：配送處在未端物流位置，屬于干線輸送29. 下列幾種描述不正確的是（）答：既時(shí)配送往往成本較低30. 每次配送時(shí)間固定而配送數(shù)量不固定的配送形式是（）答：定時(shí)配送31. 配送中心的一些必要的崗位設(shè)置應(yīng)由配送中心的（）來(lái)決定答：作業(yè)流程32. 配送需求計(jì)劃（）答：銷(xiāo)售商的銷(xiāo)售預(yù)測(cè)33. 長(zhǎng)期占用資金，是（）不合理的表現(xiàn)。答：經(jīng)營(yíng)觀念34. （）不屬于配送訂單處理程序答：訂單補(bǔ)貨35. 膠帶輸送機(jī)一般可在（）傾斜的狀況下，以高速、低噪聲輸送散裝、小件物品。答：15？20？36. 可輸送長(zhǎng)條形貸物的鏈條輸送機(jī)是（）答：簡(jiǎn)單式37. 選擇自動(dòng)分揀機(jī)時(shí)，一般需要考慮下列因素，除了（）以外。答：人員操作能力38. 下列屬于配送中心輸送機(jī)械的是（）答：斗式提升機(jī)39. 自動(dòng)分揀工作流程是（）答：合流分揀信號(hào)輸入分揀和分流分運(yùn)40. 以貸主為主體的協(xié)同配送不包括（）答：運(yùn)送業(yè)者41. 可以使揀取與搬運(yùn)作業(yè)單元化和揀取作業(yè)單純化的分區(qū)方式是（）答：按揀貨單位分區(qū) 42. 在配送中心客戶要求對(duì)貸物進(jìn)行加工、包裝等作業(yè)與管理的崗位應(yīng)該是（）答：加工管理組43. 以下對(duì)批量揀取描述，不正確的是（）答：有利于進(jìn)行揀取路線規(guī)劃，減少不必要的重復(fù)行走44. 適合于周期性配送的分批方式是（）答：總合計(jì)量分批45. 職能部門(mén)從計(jì)劃、預(yù)測(cè)、客戶服務(wù)、成本分析等為配送中心經(jīng)理、各主管提出建議和意見(jiàn)的配送中答：參謀型46. 配送中心如果庫(kù)存過(guò)大時(shí)強(qiáng)迫客戶接貸來(lái)緩解自己的庫(kù)存壓力，是（）不合理的表現(xiàn)。答：經(jīng)營(yíng)觀念47. 下列描述正確的是（）答：配送的價(jià)格應(yīng)低于客戶自己進(jìn)貨、提貨、運(yùn)送等成本總和48. 班輪運(yùn)費(fèi)按貸物的重量體積，（）計(jì)算運(yùn)費(fèi)答：選擇其中收取運(yùn)旨較高者49. 運(yùn)輸合同中最基本的條款是（）答：承運(yùn)人的嚴(yán)格責(zé)任和限額賠償責(zé)任并存50. 貸物運(yùn)輸?shù)倪\(yùn)費(fèi)應(yīng)該（）答：托運(yùn)單裝貨單貨票提貨單51. 下列幾種公路運(yùn)費(fèi)的有關(guān)規(guī)定描述正確的是（）答：因托運(yùn)人要求對(duì)車(chē)輛改裝、拆卸、還原，其費(fèi)用由托運(yùn)人負(fù)擔(dān)52. 班輪運(yùn)輸?shù)倪\(yùn)費(fèi)應(yīng)該（）答：裝卸費(fèi)，但不計(jì)滯期費(fèi)，帶遣費(fèi)53. 對(duì)由于自然災(zāi)害造成的單獨(dú)海損不承擔(dān)賠償責(zé)任的險(xiǎn)種是（）答：海上運(yùn)輸平安險(xiǎn)54. 貸物動(dòng)輸?shù)谋ｋU(xiǎn)索賠程序是損失通知、向承運(yùn)人等提出索賠、采取合理的施救整理措施和（）答：備妥索賠單證55. 航空貸物運(yùn)輸保險(xiǎn)責(zé)任期間是“倉(cāng)到倉(cāng)”。如未進(jìn)倉(cāng)，則以被保險(xiǎn)貸物是在最后卸載地卸離飛機(jī)滿答：56. 國(guó)內(nèi)陸路與水路運(yùn)輸貸物運(yùn)抵目的地后，如果收貸人未及時(shí)提取貸物，該承運(yùn)合同下的保險(xiǎn)單責(zé)任答：15天57. 公路運(yùn)輸、鐵路運(yùn)輸、航空運(yùn)輸、海洋提單運(yùn)輸都是以（）作為運(yùn)輸合同的契約合同。答：貨物運(yùn)輸單據(jù)58. 貸運(yùn)合同中最為復(fù)雜的是（）答：國(guó)際海運(yùn)合同 59. 國(guó)際空運(yùn)輸中最主要的單據(jù)是（）答：航空運(yùn)單60. 某外貿(mào)公司出口科威特文具1000箱，每箱毛重30kg、體積0.35m3.貸物從大連港運(yùn)到科威特港答：283561. 將俄羅斯安加爾斯每日盛產(chǎn)的100萬(wàn)桶石油運(yùn)往中國(guó)大慶，選擇（）方式比較合適答：管道運(yùn)輸62. “四就”直撥運(yùn)輸主要減少中轉(zhuǎn)次數(shù)和（），提高運(yùn)輸作業(yè)效率答：運(yùn)輸環(huán)節(jié)63. （）是銷(xiāo)售型配送中心的特征答：A 提供一體化服務(wù)C 開(kāi)展配送活動(dòng)為營(yíng)銷(xiāo)手段64. 關(guān)于車(chē)輛配載以下說(shuō)法正確的是（）答：A 重不壓輕，大不壓小B 滲水貨物與易受潮貨物不能混裝D 貨物之間應(yīng)留有空隙并適當(dāng)襯墊65. 配送模式一般包括（）答：A 直接配送模式B 直通配送模式C 流通加工型配送模式D 儲(chǔ)存配送模式66. 配送服務(wù)方式主要有定時(shí)配送、準(zhǔn)時(shí)配送以及（）等答：A 快遞配送B 定量配送C 定時(shí)定量配送D 定時(shí)定路線配送67. 屬于專(zhuān)業(yè)配送的主要有（）答：A 中小件雜貨配送B 金屬材料配送C 燃料煤配送68. 以下屬于送貨作業(yè)的特點(diǎn)的是（）答：B 時(shí)效性C 便利性D 經(jīng)濟(jì)性69. 常用原補(bǔ)貨方式有（）答：1、整箱補(bǔ)貨2、托盤(pán)補(bǔ)貨70. 配貨專(zhuān)業(yè)配送的主要有（）答：A 個(gè)裝B 內(nèi)裝C 外裝71. 以下屬于配送單據(jù)的是（）答：A 駕駛記錄表C配送調(diào)度單D送貨單72. （）是區(qū)域配送中心的特征答：A 較強(qiáng)輻射能力 C 較強(qiáng)的庫(kù)存 73. 送貨作業(yè)是配送中心最終直接面對(duì)用戶的服務(wù)，具有（）和經(jīng)濟(jì)性等特點(diǎn)。答：B 可靠性C 溝通性D 便利性74. 流能加工的方式包括（）答：A 生產(chǎn)資料的流通加工方式B 消費(fèi)（生活）的流通加工方式C 生鮮食品的流通加工方式75. 專(zhuān)業(yè)配送中心可以分為（）答：A 綜合某一專(zhuān)業(yè)的多種物資進(jìn)行配送的配送中心C 不從事經(jīng)營(yíng)的服務(wù)型配送中心76. 配送系統(tǒng)節(jié)點(diǎn)活動(dòng)的場(chǎng)所包括（）答：A 物品的供方 B運(yùn)輸車(chē)隊(duì)77. 流通加工管理工作包括（）答：A計(jì)劃管理 B 生產(chǎn)管理 C成本管理 D 銷(xiāo)售管理 78. 配送路線優(yōu)化是（）答：A在一段路線上，送貨客戶最密C 在確定時(shí)間內(nèi)，送貨客戶最密79. 配送計(jì)劃表的內(nèi)容包括（）答：A 商品規(guī)格B 商品數(shù)量 D 配送時(shí)間 80. 與其他物流功能要素比，配送特有的功能是（）答：B 分揀 C 配貨81. 自動(dòng)分揀系統(tǒng)的主要特點(diǎn)的是（）答：A能連續(xù)、大批量地分揀貨物B 分揀誤差極低D 分揀作業(yè)基本實(shí)現(xiàn)無(wú)人化82. 對(duì)配送貨物進(jìn)行重新包裝、打捆是為了（）答：A實(shí)現(xiàn)成組化搬運(yùn)B 降低貨損83. 配送中心統(tǒng)一進(jìn)貨的主要目的是（）答：A 避免庫(kù)存分散 C降低整體庫(kù)存水平84. 組織合理化配送作業(yè)包括（）答：A訂貨發(fā)貨合理化B商品檢驗(yàn)合理化C備貨作業(yè)合理化85. 下列（）是社會(huì)運(yùn)力節(jié)約標(biāo)志。答：B 社會(huì)車(chē)輛總數(shù)增加，且運(yùn)量增加C 一家一戶自提自運(yùn)減少D社會(huì)車(chē)輛空駛減少86. 下列（）是配送企業(yè)經(jīng)營(yíng)觀念不合理的表現(xiàn)答：A 長(zhǎng)期占用客戶資金B(yǎng)庫(kù)存過(guò)大時(shí)強(qiáng)迫客戶接貨來(lái)緩解自己的庫(kù)存壓力C將客戶委托資源挪作他用而獲利87. 下列哪些屬于訂單分批作業(yè)（）答：A總合計(jì)量分批B定時(shí)分批C智慧型分批88. 連續(xù)檢測(cè)補(bǔ)貨系統(tǒng)有（）答：B訂貨點(diǎn)補(bǔ)貨系統(tǒng)D經(jīng)常庫(kù)存與安全庫(kù)存補(bǔ)貨系統(tǒng)89. 配送中心送貨合理化指標(biāo)主要有（）答：A車(chē)輛平均作業(yè)量B空駛率C外包車(chē)比率D配送延誤率90. 配送中心進(jìn)貨作業(yè)包括（）答：A訂貨C接貨D驗(yàn)收入庫(kù)91. （）屬于按揀貨單位分區(qū)答：A箱裝揀貨區(qū)B單車(chē)揀貨區(qū)D臺(tái)車(chē)揀貨區(qū)92. 配送中心貨物數(shù)量驗(yàn)收方法包括（）答：A標(biāo)記法C分批清點(diǎn)法D定額裝載法93. 國(guó)際多式聯(lián)運(yùn)經(jīng)營(yíng)人的責(zé)任范圍與賠償限額分為（）答：A統(tǒng)一責(zé)任制B分段責(zé)任制C混合責(zé)任制94. 鐵路運(yùn)輸?shù)膬?yōu)點(diǎn)（）答：A大運(yùn)量、長(zhǎng)距離B運(yùn)輸變動(dòng)成本C快速準(zhǔn)時(shí)D運(yùn)營(yíng)技術(shù)指標(biāo)高95. 貨物運(yùn)輸按照運(yùn)輸作用，主要分為（）兩類(lèi)答：A集貨運(yùn)輸C配送運(yùn)輸96. 海洋運(yùn)輸?shù)膬?yōu)點(diǎn)（）答：A運(yùn)輸距離最長(zhǎng)、運(yùn)量最大B運(yùn)輸成本最低C國(guó)際貿(mào)易的主要運(yùn)輸方式97. 托運(yùn)單的作用主要是（）答：A托運(yùn)人與承運(yùn)人運(yùn)輸合同C交貨憑證與貨物收據(jù)請(qǐng)您刪除一下內(nèi)容，O(_)O謝謝！2016年中央電大期末復(fù)習(xí)考試小抄大全，電大期末考試必備小抄，電大考試必過(guò)小抄Acetylcholine is a neurotransmitter released from nerve endings (terminals) in both the peripheral and the central nervous systems. It is synthesized within the nerve terminal from choline, taken up from the tissue fluid into the nerve ending by a specialized transport mechanism. The enzyme necessary for this synthesis is formed in the nerve cell body and passes down the axon to its end, carried in the axoplasmic flow, the slow movement of intracellular substance (cytoplasm). Acetylcholine is stored in the nerve terminal, sequestered in small vesicles awaiting release. When a nerve action potential reaches and invades the nerve terminal, a shower of acetylcholine vesicles is released into the junction (synapse) between the nerve terminal and the effector cell which the nerve activates. This may be another nerve cell or a muscle or gland cell. Thus electrical signals are converted to chemical signals, allowing messages to be passed between nerve cells or between nerve cells and non-nerve cells. This process is termed chemical neurotransmission and was first demonstrated, for nerves to the heart, by the German pharmacologist Loewi in 1921. Chemical transmission involving acetylcholine is known as cholinergic. Acetylcholine acts as a transmitter between motor nerves and the fibres of skeletal muscle at all neuromuscular junctions. At this type of synapse, the nerve terminal is closely apposed to the cell membrane of a muscle fibre at the so-called motor end plate. On release, acetylcholine acts almost instantly, to cause a sequence of chemical and physical events (starting with depolarization of the motor endplate) which cause contraction of the muscle fibre. This is exactly what is required for voluntary muscles in which a rapid response to a command is required. The action of acetylcholine is terminated rapidly, in around 10 milliseconds; an enzyme (cholinesterase) breaks the transmitter down into choline and an acetate ion. The choline is then available for re-uptake into the nerve terminal. These same principles apply to cholinergic transmission at sites other than neuromuscular junctions, although the structure of the synapses differs. In the autonomic nervous system these include nerve-to-nerve synapses at the relay stations (ganglia) in both the sympathetic and the parasympathetic divisions, and the endings of parasympathetic nerve fibres on non-voluntary (smooth) muscle, the heart, and glandular cells; in response to activation of this nerve supply, smooth muscle contracts (notably in the gut), the frequency of heart beat is slowed, and glands secrete. Acetylcholine is also an important transmitter at many sites in the brain at nerve-to-nerve synapses. To understand how acetylcholine brings about a variety of effects in different cells it is necessary to understand membrane receptors. In post-synaptic membranes (those of the cells on which the nerve fibres terminate) there are many different sorts of receptors and some are receptors for acetylcholine. These are protein molecules that react specifically with acetylcholine in a reversible fashion. It is the complex of receptor combined with acetylcholine which brings about a biophysical reaction, resulting in the response from the receptive cell. Two major types of acetylcholine receptors exist in the membranes of cells. The type in skeletal muscle is known as nicotinic; in glands, smooth muscle, and the heart they are muscarinic; and there are some of each type in the brain. These terms are used because nicotine mimics the action of acetylcholine at nicotinic receptors, whereas muscarine, an alkaloid from the mushroom Amanita muscaria, mimics the action of acetylcholine at the muscarinic receptors. Acetylcholine is the neurotransmitter produced by neurons referred to as cholinergic neurons. In the peripheral nervous system acetylcholine plays a role in skeletal muscle movement, as well as in the regulation of smooth muscle and cardiac muscle. In the central nervous system acetylcholine is believed to be involved in learning, memory, and mood. Acetylcholine is synthesized from choline and acetyl coenzyme A through the action of the enzyme choline acetyltransferase and becomes packaged into membrane-boundvesicles. After the arrival of a nerve signal at the termination of an axon, the vesicles fuse with the cell membrane, causing the release of acetylcholine into thesynaptic cleft. For the nerve signal to continue, acetylcholine must diffuse to another nearby neuron or muscle cell, where it will bind and activate areceptorprotein. There are two main types of cholinergic receptors, nicotinic and muscarinic. Nicotinic receptors are located at synapses between two neurons and at synapses between neurons and skeletal muscle cells. Upon activation a nicotinic receptor acts as a channel for the movement of ions into and out of the neuron, directly resulting indepolarizationof the neuron. Muscarinic receptors, located at the synapses of nerves with smooth or cardiac muscle, trigger a chain of chemical events referred to as signal transduction. For a cholinergic neuron to receive another impulse, acetylcholine must be released from the receptor to which it has bound. This will only happen if the concentration of acetylcholine in the synaptic cleft is very low. Low synaptic concentrations of acetylcholine can be maintained via a hydrolysis reaction catalyzed by the enzyme acetylcholinesterase. This enzyme hydrolyzes acetylcholine into acetic acid and choline. If acetylcholinesterase activity is inhibited, the synaptic concentration of acetylcholine will remain higher than normal. If this inhibition is irreversible, as in the case of exposure to many nerve gases and some pesticides, sweating, bronchial constriction, convulsions, paralysis, and possibly death can occur. Although irreversible inhibition is dangerous, beneficial effects may be derived from transient (reversible) inhibition. Drugs that inhibit acetylcholinesterase in a reversible manner have been shown to improve memory in some people with Alzheimers disease. abstract expressionism, movement of abstract painting that emerged in New York City during the mid-1940s and attained singular prominence in American art in the following decade; also called action painting and the New York school. It was the first important school in American painting to declare its independence from European styles and to influence the development of art abroad. Arshile Gorky first gave impetus to the movement. His paintings, derived at first from the art of Picasso, Mir, and surrealism, became more personally expressive. Jackson Pollocks turbulent yet elegant abstract paintings, which were created by spattering paint on huge canvases placed on the floor, brought abstract expressionism before a hostile public. Willem de Koonings first one-man show in 1948 established him as a highly influential artist. His intensely complicated abstract paintings of the 1940s were followed by images of Woman, grotesque versions of buxom womanhood, which were virtually unparalleled in the sustained savagery of their execution. Painters such as Philip Guston and Franz Kline turned to the abstract late in the 1940s and soon developed strikingly original stylesthe former, lyrical and evocative, the latter, forceful and boldly dramatic. Other important artists involved with the movement included Hans Hofmann, Robert Motherwell, and Mark Rothko; among other major abstract expressionists were such painters as Clyfford Still, Theodoros Stamos, Adolph Gottlieb, Helen Frankenthaler, Lee Krasner, and Esteban Vicente. Abstract expressionism presented a broad range of stylistic diversity within its largely, though not exclusively, nonrepresentational framework. For example, the expressive violence and activity in paintings by de Kooning or Pollock marked the opposite end of the pole from the simple, quiescent images of Mark Rothko. Basic to most abstract expressionist painting were the attention paid to surface qualities, i.e., qualities of brushstroke and texture; the use of huge canvases; the adoption of an approach to space in which all parts of the canvas played an equally vital role in the total work; the harnessing of accidents that occurred during the process of painting; the glorification of the act of painting itself as a means of visual communication; and the attempt to transfer pure emotion directly onto the canvas. The movement had an inestimable influence on the many varieties of work that followed it, especially in the way its proponents used color and materials. Its essential energy transmitted an enduring excitement to the American art scene. Science and technology is quite a broad category, and it covers everything from studying the stars and the planets to studying molecules and viruses. Beginning with the Greeks and Hipparchus, continuing through Ptolemy, Copernicus and Galileo, and today with our work on the International Space Station, man continues to learn more and more about the heavens. From here, we look inward to biochemistry and biology. To truly understand biochemistry, scientists study and see the unseen bystudying the chemistry of biological processes. This science, along with biophysics, aims to bring a better understanding of how bodies work from how we turn food into energy to how nerve impulses transmit.analytic geometry, branch ofgeometryin which points are represented with respect to a coordinate system, such asCartesian coordinates, and in which the approach to geometric problems is primarily algebraic. Its most common application is in the representation of equations involving two or three variables as curves in two or three dimensions or surfaces in three dimensions. For example, the linear equationax+by+c=0 represents a straight line in thexy-plane, and the linear equationax+by+cz+d=0 represents a plane in space, wherea, b, c,anddare constant numbers (coefficients). In this way a geometric problem can be translated into an algebraic problem and the methods of algebra brought to bear on its solution. Conversely, the solution of a problem in algebra, such as finding the roots of an equation or system of equations, can be estimated or sometimes given exactly by geometric means, e.g., plotting curves and surfaces and determining points of intersection. In plane analytic geometry a line is frequently described in terms of its slope, which expresses its inclination to the coordinate axes; technically, the slopemof a straight line is the (trigonometric) tangent of the angle it makes with thex-axis. If the line is parallel to thex-axis, its slope is zero. Two or more lines with equal slopes are parallel to one another. In general, the slope of the line through the points (x1,y1) and (x2,y2) is given bym= (y2-y1) / (x2-x1). The conic sections are treated in analytic geometry as the curves corresponding to the general quadratic equationax2+bxy+cy2+dx+ey+f=0, wherea, b, fare constants anda, b,andcare not all zero. In solid analytic geometry the orientation of a straight line is given not by one slope but by its direction cosines, , , and , the cosines of the angles the line makes with thex-, y-,andz-axes, respectively; these satisfy the relationship 2+2+2= 1. In the same way that the conic sections are studied in two dimensions, the 17 quadric surfaces, e.g., the ellipsoid, paraboloid, and elliptic paraboloid, are studied in solid analytic geometry in terms of the general equationax2+by2+cz2+dxy+exz+fyz+px+qy+rz+s=0. The methods of analytic geometry have been generalized to four or more dimensions and have been combined with other branches of geometry. Analytic geometry was introduced by RenDescartesin 1637 and was of fundamental importance in the development of thecalculusby Sir Isaac Newton and G. W. Leibniz in the late 17th cent. More recently it has served as the basis for the modern development and exploitation ofalgebraic geometry. circle, closed plane curve consisting of all points at a given distance from some fixed point, called the center. A circle is a conic section cut by a plane perpendicular to the axis of the cone. The term circle is also used to refer to the region enclosed by the curve, more properly called a circular region. The radius of a circle is any line segment connecting the center and a point on the curve; the term is also used for the length r of this segment, i.e., the common distance of all points on the curve from the center. Similarly, the circumference of a circle is either the curve itself or its length of arc. A line segment whose two ends lie on the circumference is a chord; a chord through the center is the diameter. A secant is a line of indefinite length intersecting the circle at two points, the segment of it within the circle being a chord. A tangent to a circle is a straight line touching the circle at only one point, the point of contact, or tangency, and is always perpendicular to the radius drawn to this point. A circle is inscribed in a polygon if each side of the polygon is tangent to the circle; a circle is circumscribed about a polygon if all the vertices of the polygon lie on the circumference. The length of the circumference C of a circle is equal to (see pi) times twice the radius distance r, or C=2r. The area A bounded by a circle is given by A=r2. Greek geometry left many unsolved problems about circles, including the problem of squaring the circle, i.e., constructing a square with an area equal to that of a given circle, using only a straight edge and compass; it was finally proved impossible in the late 19th cent. (see geometric problems of antiquity). In modern mathematics the circle is the basis for such theories as inversive geometry and certain non-Euclidean geometries. The circle figures significantly in many cultures. In religion and art it frequently symbolizes heaven, eternity, or the universe.