什么是正切值求数学学霸帮忙讲解一下初中三角函数知识点和高中三角函数的初步 +初中三角函数的知识点有哪些，怎么学习
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\u4f59\u5f26\uff08cos\uff09\u7b49\u4e8e\u90bb\u8fb9\u6bd4\u659c\u8fb9\uff1bcosA=b/c
\u6b63\u5207\uff08tan\uff09\u7b49\u4e8e\u5bf9\u8fb9\u6bd4\u90bb\u8fb9\uff1btanA=a/b
\u4f59\u5207\uff08cot\uff09\u7b49\u4e8e\u90bb\u8fb9\u6bd4\u5bf9\u8fb9\uff1bcotA=b/a
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sin30\u00b0=1/2
sin45\u00b0=\u221a2/2
sin60\u00b0=\u221a3/2
cos30\u00b0=\u221a3/2
cos45\u00b0=\u221a2/2
cos60\u00b0=1/2
tan30\u00b0=\u221a3/3
tan45\u00b0=1
tan60\u00b0=\u221a3[1]
cot30\u00b0=\u221a3
cot45\u00b0=1
cot60\u00b0=\u221a3/3
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sin(A+B)=sinAcosB+cosAsinB
sin(A-B)=sinAcosB-sinBcosA
cos(A+B)=cosAcosB-sinAsinB
cos(A-B)=cosAcosB+sinAsinB
tan(A+B)=(tanA+tanB)/(1-tanAtanB)
tan(A-B)=(tanA-tanB)/(1+tanAtanB)
ctg(A+B)=(ctgActgB-1)/(ctgB+ctgA)
ctg(A-B)=(ctgActgB+1)/(ctgB-ctgA)
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sin(A/2)=\u221a((1-cosA)/2) sin(A/2)=-\u221a((1-cosA)/2)
cos(A/2)=\u221a((1+cosA)/2) cos(A/2)=-\u221a((1+cosA)/2)
tan(A/2)=\u221a((1-cosA)/((1+cosA))
tan(A/2)=-\u221a((1-cosA)/((1+cosA))
ctg(A/2)=\u221a((1+cosA)/((1-cosA))
ctg(A/2)=-\u221a((1+cosA)/((1-cosA))
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2sinAcosB=sin(A+B)+sin(A-B) 2cosAsinB=sin(A+B)-sin(A-B) 2cosAcosB=cos(A+B)-sin(A-B) -2sinAsinB=cos(A+B)-cos(A-B) sinA+sinB=2sin((A+B)/2)cos((A-B)/2 cosA+cosB=2cos((A+B)/2)sin((A-B)/2) tanA+tanB=sin(A+B)/cosAcosB tanA-tanB=sin(A-B)/cosAcosB ctgA+ctgBsin(A+B)/sinAsinB - ctgA+ctgBsin(A+B)/sinAsinB \u4e09\u3001\u9510\u89d2\u4e09\u89d2\u51fd\u6570\u56fe\u50cf\u548c\u6027\u8d28
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\u521d\u4e2d\u6570\u5b66\u5b66\u4e60\u8bfe\u7a0b\u5206\u7f51\u7edc\u548c\u9762\u6388\uff0c\u6709\u5c0f\u73ed\u5236\uff0c\u5927\u73ed\u5236\uff0c1\u5bf91\uff0c1\u5bf93\u5f62\u5f0f\uff0c\u6388\u8bfe\u6821\u533a\u5206\u5e03\u5728\u4e0a\u6d77\u5404\u4e2a\u5730\u57df\uff0c\u9762\u6388\u73ed\u8bfe\u65f6\u4ee5\u6602\u7acb\u65b0\u8bfe\u7a0b\u5b98\u7f51\u9881\u5e03\u8bfe\u65f6\u4e3a\u4e3b\uff0c\u5177\u4f53\u8d39\u7528\u53ef\u54a8\u8be2\u5728\u7ebf\u5ba2\u670d\u6216\u62e8\u6253\u70ed\u7ebf4008-770-970\u3002
\u6211\u4eec\u63a5\u89e6\u521d\u4e2d\u4e09\u89d2\u51fd\u6570\u4e4b\u65f6\uff0c\u8981\u4e86\u89e3\u5b83\u662f\u9ad8\u4e2d\u4e09\u89d2\u51fd\u6570\u7684\u57fa\u7840\uff0c\u662f\u9ad8\u4e2d\u6570\u5b66\u7684\u91cd\u96be\u70b9\u548c\u5fc5\u8003\u70b9\u3002\u4e09\u89d2\u51fd\u6570\u662f\u8d85\u8d8a\u51fd\u6570\u4e00\u7c7b\u51fd\u6570\uff0c\u5c5e\u4e8e\u521d\u7b49\u51fd\u6570\u3002\u4efb\u610f\u89d2\u7684\u96c6\u5408\u4e0e\u4e00\u4e2a\u6bd4\u503c\u7684\u96c6\u5408\u53d8\u91cf\u4e4b\u95f4\u7684\u6620\u5c04\u5c31\u662f\u4e09\u89d2\u51fd\u6570\u7684\u672c\u8d28\u3002\u901a\u5e38\u7528\u5e73\u9762\u76f4\u89d2\u5750\u6807\u7cfb\u6765\u5b9a\u4e49\u4e09\u89d2\u51fd\u6570\uff0c\u5b9a\u4e49\u662f\u6574\u4e2a\u5b9e\u6570\u57df\u3002\u521d\u4e2d\u4e09\u89d2\u51fd\u6570\u5305\u542b\u516d\u79cd\u57fa\u672c\u51fd\u6570\uff1a\u6b63\u5207\u3001\u4f59\u5207\u3001\u6b63\u5f26\u3001\u4f59\u5f26\u3001\u6b63\u5272\u3001\u4f59\u5272\u3002
\u3000\u3000\u9ad8\u4e2d\u4e09\u89d2\u51fd\u6570\uff0c\u5982\u4e00\u5934\u62e6\u8def\u864e\uff0c\u8ba9\u5f88\u591a\u5b66\u751f\u671b\u800c\u5374\u6b65\u3001\u754f\u60e7\u4e0d\u5df2\u3002\u521d\u4e2d\u4e09\u89d2\u51fd\u6570\u5b66\u5f97\u597d\u574f\uff0c\u76f4\u63a5\u5f71\u54cd\u9ad8\u4e2d\u4e09\u89d2\u51fd\u6570\u7684\u5b66\u4e60\uff0c\u56e0\u4e3a\u521d\u4e2d\u662f\u9ad8\u4e2d\u7684\u57fa\u7840\u3002\u90a3\u4e48\uff0c\u521d\u4e2d\u4e09\u89d2\u51fd\u6570\u77e5\u8bc6\u70b9\u6709\u54ea\u4e9b\uff1f\u521d\u4e2d\u4e09\u89d2\u51fd\u6570\u516c\u5f0f\u6709\u54ea\u4e9b\uff1f\u5982\u4f55\u8bb0\u5fc6\u8fd9\u4e9b\u516c\u5f0f\uff1f\u521d\u4e2d\u4e09\u89d2\u51fd\u6570\u600e\u4e48\u5b66\u624d\u80fd\u4e3a\u9ad8\u4e2d\u6253\u597d\u57fa\u7840\uff1f\u4e0d\u7528\u62c5\u5fc3\uff0c\u4e0b\u9762\u4e3a\u60a8\u89e3\u7b54\u3002
\u6b65\u9aa4/\u65b9\u6cd511\u3001\u52fe\u80a1\u5b9a\u7406\uff1a\u76f4\u89d2\u4e09\u89d2\u5f62\u4e24\u76f4\u89d2\u8fb9a\u3001b\u7684\u5e73\u65b9\u548c\u7b49\u4e8e\u659c\u8fb9c\u7684\u5e73\u65b9a2+b2=c2\u3002
\u3000\u30002\u3001\u5982\u4e0b\u56fe\uff0c\u5728Rt\u25b3ABC\u4e2d\uff0c\u2220C\u4e3a\u76f4\u89d2\uff0c\u5219\u2220A\u7684\u9510\u89d2\u4e09\u89d2\u51fd\u6570\u4e3a(\u2220A\u53ef\u6362\u6210\u2220B)\uff1a
\u30003\u3001\u4efb\u610f\u9510\u89d2\u7684\u6b63\u5f26\u503c\u7b49\u4e8e\u5b83\u7684\u4f59\u89d2\u7684\u4f59\u5f26\u503c\uff1b\u4efb\u610f\u9510\u89d2\u7684\u4f59\u5f26\u503c\u7b49\u4e8e\u5b83\u7684\u4f59\u89d2\u7684\u6b63\u5f26\u503c\u3002
4\u3001\u4efb\u610f\u9510\u89d2\u7684\u6b63\u5207\u503c\u7b49\u4e8e\u5b83\u7684\u4f59\u89d2\u7684\u4f59\u5207\u503c\uff1b\u4efb\u610f\u9510\u89d2\u7684\u4f59\u5207\u503c\u7b49\u4e8e\u5b83\u7684\u4f59\u89d2\u7684\u6b63\u5207\u503c\u3002
\u30005\u30010\u00b0\u300130\u00b0\u300145\u00b0\u300160\u00b0\u300190\u00b0\u7279\u6b8a\u89d2\u7684\u4e09\u89d2\u51fd\u6570\u503c(\u91cd\u8981)
\u30006\u3001\u6b63\u5f26\u3001\u4f59\u5f26\u7684\u589e\u51cf\u6027\uff1a
\u3000\u3000\u5f530\u00b0\u2264\u03b1\u226490\u00b0\u65f6\uff0csin\u03b1\u968f\u03b1\u7684\u589e\u5927\u800c\u589e\u5927\uff0ccos\u03b1\u968f\u03b1\u7684\u589e\u5927\u800c\u51cf\u5c0f\u3002
\u3000\u30007\u3001\u6b63\u5207\u3001\u4f59\u5207\u7684\u589e\u51cf\u6027\uff1a\u5f530\u00b0<\u03b1<90\u00b0\u65f6\uff0ctan\u03b1\u968f\u03b1\u7684\u589e\u5927\u800c\u589e\u5927\uff0ccot\u03b1\u968f\u03b1\u7684\u589e\u5927\u800c\u51cf\u5c0f\u3002
\u3000\u63a5\u4e0b\u6765\u4f60\u8981\u719f\u6089\u521d\u4e2d\u4e09\u89d2\u51fd\u6570\u516c\u5f0f\u3002
\u3000\u3000\u4e09\u89d2\u51fd\u6570\u6052\u7b49\u53d8\u5f62\u516c\u5f0f\uff1a
\u3000\u3000\u00b7\u521d\u4e2d\u4e09\u89d2\u51fd\u6570\u4e24\u89d2\u548c\u4e0e\u5dee\u7684\u4e09\u89d2\u51fd\u6570\uff1a
\u3000\u3000cos(\u03b1+\u03b2)=cos\u03b1\u00b7cos\u03b2-sin\u03b1\u00b7sin\u03b2
\u3000\u3000cos(\u03b1-\u03b2)=cos\u03b1\u00b7cos\u03b2+sin\u03b1\u00b7sin\u03b2
\u3000\u3000sin(\u03b1\u00b1\u03b2)=sin\u03b1\u00b7cos\u03b2\u00b1cos\u03b1\u00b7sin\u03b2
\u3000\u3000tan(\u03b1+\u03b2)=(tan\u03b1+tan\u03b2)/(1-tan\u03b1\u00b7tan\u03b2)
\u3000\u3000tan(\u03b1-\u03b2)=(tan\u03b1-tan\u03b2)/(1+tan\u03b1\u00b7tan\u03b2)
\u3000\u3000\u00b7\u521d\u4e2d\u4e09\u89d2\u51fd\u6570\u500d\u89d2\u516c\u5f0f\uff1a
\u3000\u3000sin(2\u03b1)=2sin\u03b1\u00b7cos\u03b1
\u3000\u3000cos(2\u03b1)=cos^2(\u03b1)-sin^2(\u03b1)=2cos^2(\u03b1)-1=1-2sin^2(\u03b1)
\u3000\u3000tan(2\u03b1)=2tan\u03b1/[1-tan^2(\u03b1)]
\u3000\u3000\u00b7\u521d\u4e2d\u4e09\u89d2\u51fd\u6570\u4e09\u500d\u89d2\u516c\u5f0f\uff1a
\u3000\u3000sin3\u03b1=3sin\u03b1-4sin^3(\u03b1)
\u3000\u3000cos3\u03b1=4cos^3(\u03b1)-3cos\u03b1
\u3000\u3000\u00b7\u521d\u4e2d\u4e09\u89d2\u51fd\u6570\u534a\u89d2\u516c\u5f0f\uff1a
\u3000\u3000sin^2(\u03b1/2)=(1-cos\u03b1)/2
\u3000\u3000cos^2(\u03b1/2)=(1+cos\u03b1)/2
\u3000\u3000tan^2(\u03b1/2)=(1-cos\u03b1)/(1+cos\u03b1)
\u3000\u3000tan(\u03b1/2)=sin\u03b1/(1+cos\u03b1)=(1-cos\u03b1)/sin\u03b1
\u3000\u3000\u00b7\u521d\u4e2d\u4e09\u89d2\u51fd\u6570\u4e07\u80fd\u516c\u5f0f\uff1a
\u3000\u3000sin\u03b1=2tan(\u03b1/2)/[1+tan^2(\u03b1/2)]
\u3000\u3000cos\u03b1=[1-tan^2(\u03b1/2)]/[1+tan^2(\u03b1/2)]
\u3000\u3000tan\u03b1=2tan(\u03b1/2)/[1-tan^2(\u03b1/2)]
\u3000\u3000\u00b7\u521d\u4e2d\u4e09\u89d2\u51fd\u6570\u79ef\u5316\u548c\u5dee\u516c\u5f0f\uff1a
\u3000\u3000sin\u03b1\u00b7cos\u03b2=(1/2)[sin(\u03b1+\u03b2)+sin(\u03b1-\u03b2)]
\u3000\u3000cos\u03b1\u00b7sin\u03b2=(1/2)[sin(\u03b1+\u03b2)-sin(\u03b1-\u03b2)]
\u3000\u3000cos\u03b1\u00b7cos\u03b2=(1/2)[cos(\u03b1+\u03b2)+cos(\u03b1-\u03b2)]
\u3000\u3000sin\u03b1\u00b7sin\u03b2=-(1/2)[cos(\u03b1+\u03b2)-cos(\u03b1-\u03b2)]
\u3000\u3000\u00b7\u521d\u4e2d\u4e09\u89d2\u51fd\u6570\u548c\u5dee\u5316\u79ef\u516c\u5f0f\uff1a
\u3000\u3000sin\u03b1+sin\u03b2=2sin[(\u03b1+\u03b2)/2]cos[(\u03b1-\u03b2)/2]
\u3000\u3000sin\u03b1-sin\u03b2=2cos[(\u03b1+\u03b2)/2]sin[(\u03b1-\u03b2)/2]
\u3000\u3000cos\u03b1+cos\u03b2=2cos[(\u03b1+\u03b2)/2]cos[(\u03b1-\u03b2)/2]
\u3000\u3000cos\u03b1-cos\u03b2=-2sin[(\u03b1+\u03b2)/2]sin[(\u03b1-\u03b2)/2]
\u6700\u540e\uff0c\u521d\u4e2d\u4e09\u89d2\u51fd\u6570\u600e\u4e48\u5b66\u624d\u80fd\u638c\u63e1\u597d\uff0c\u624d\u80fd\u4e3a\u9ad8\u4e2d\u4e09\u89d2\u51fd\u6570\u6253\u4e0b\u624e\u5b9e\u57fa\u7840\uff1f
\u3000\u3000\u65e2\u7136\u8c08\u5230\u521d\u4e2d\u4e09\u89d2\u51fd\u6570\u5b9e\u4e3a\u9ad8\u4e2d\u4e09\u89d2\u51fd\u6570\u7684\u57fa\u7840\uff0c\u6211\u7ed9\u5927\u5bb6\u4e3e\u4e00\u4e2a\u9ad8\u4e2d\u7684\u4f8b\u5b50\uff1a
\u3000\u3000\u6211\u8bb0\u5f97\u6709\u4e00\u5e74\uff0c\u6709\u4e2a\u9ad8\u4e00\u7684\u5b66\u751f\u627e\u5230\u6211\uff0c\u8bf4\u9ad8\u4e00\u6570\u5b66\u5b66\u5f97\u5f88\u4e00\u822c\uff0c\u5e0c\u671b\u6211\u80fd\u7ed9\u4ed6\u70b9\u62e8\u70b9\u62e8\u3002\u4ed6\u5c31\u62ff\u7740\u4e00\u5957\u5377\u5b50\u6765\u5230\u6211\u529e\u516c\u5ba4\uff0c\u4e0a\u9762\u6709\u4e00\u9053\u9898\u662f\uff1a
\u3000\u3000y=sinx23sinxcosx4cosx2
\u3000\u3000\u6c42\u8fd9\u4e2a\u51fd\u6570\u7684\u6700\u503c\u3002
\u3000\u3000\u6211\u4e00\u770b\u9ad8\u4e00\u7684\u5b66\u751f\uff0c\u8fde\u8fd9\u4e2a\u9898\u90fd\u4e0d\u4f1a\u505a\uff0c\u53ef\u89c1\u4ed6\u7684\u6c34\u5e73\u592a\u4e00\u822c\u4e86\u3002\u8fd9\u4e2a\u9898\u6211\u51e0\u53e5\u8bdd\u5c31\u80fd\u7ed9\u4ed6\u8bb2\u660e\u767d\uff0c\u4f46\u6211\u4e0d\u80fd\u5149\u7ed9\u4ed6\u8bb2\u8fd9\u4e2a\u9898\uff0c\u800c\u662f\u8003\u8651\u8fd9\u4e2a\u5b69\u5b50\u7684\u95ee\u9898\u51fa\u5728\u54ea\u513f\uff0c\u5426\u5219\u540c\u6837\u7684\u9898\u4ed6\u8fd8\u662f\u4e0d\u4f1a\u505a\u3002
\u3000\u3000\u6211\u5c31\u95ee\u4ed6\uff1a\u201c\u964d\u5e42\u516c\u5f0f\u4f1a\u5417\uff1f\u201d
\u3000\u3000\u4ed6\u8bf4\u4e0d\u77e5\u9053\u3002
\u3000\u3000\u6211\u5fc3\u60f3\u4eca\u5929\u662f\u78b0\u7740\u201c\u9ad8\u624b\u201d\u4e86\uff0c\u6211\u7ee7\u7eed\u95ee\uff1a\u201c\u4e09\u89d2\u51fd\u6570\u7684\u500d\u89d2\u516c\u5f0f\u4f60\u4f1a\u5417\uff1f\u201d
\u3000\u3000\u4ed6\u60f3\u4e86\u60f3\uff1a\u201c\u6ca1\u6709\u5370\u8c61\u4e86\u3002\u201d
\u3000\u3000\u6211\u7ee7\u7eed\u5f80\u56de\u63a8\uff1a\u201c\u4e24\u89d2\u548c\u4e0e\u5dee\u7684\u4e09\u89d2\u51fd\u6570\u4f60\u4f1a\u5417\uff1f\u201d
\u3000\u3000\u4ed6\u60f3\u4e86\u60f3\uff1a\u201csin\uff08\u03b1\u03b2\uff09\u597d\u50cf\u7b49\u4e8esin\u03b1sin\u03b2cos\u03b1cos\u03b2\u3002\u201d
\u3000\u3000\u6211\u90fd\u60f3\u8df3\u697c\u4e86\uff0c\u4e00\u4e2a\u9ad8\u4e00\u7684\u5b66\u751f\uff0c\u4e24\u89d2\u548c\u4e0e\u5dee\u7684\u4e09\u89d2\u51fd\u6570\u90fd\u8bb0\u4e0d\u4f4f\uff0c\u8fd8\u6709\u4ec0\u4e48\u53ef\u8bf4\u7684\uff1f\u4f46\u662f\u6211\u8fd9\u4e2a\u4eba\u4e5f\u6bd4\u8f83\u56fa\u6267\uff0c\u6211\u4e00\u822c\u8981\u5e2e\u7684\u5b66\u751f\uff0c\u4ed6\u518d\u600e\u4e48\u5dee\uff0c\u6211\u4e5f\u8981\u628a\u4ed6\u5e2e\u5230\u5e95\u3002\u6211\u60f3\u4eca\u5929\u8c41\u51fa\u53bb\u4e86\uff0c\u6211\u975e\u8981\u628a\u4ed6\u4e0d\u4f1a\u7684\u6839\u6e90\u6316\u6398\u51fa\u6765\uff0c\u7ee7\u7eed\u5f80\u56de\u9000\uff0c\u95ee\u4ed6\uff1a\u201c\u4efb\u610f\u89d2\u7684\u4e09\u89d2\u51fd\u6570\u5b9a\u7406\uff0c\u4f60\u77e5\u9053\u5427\uff1f\u201d
\u3000\u3000\u4ed6\u8bf4\u4e0d\u77e5\u9053\u3002
\u3000\u3000\u518d\u5f80\u56de\u9000\uff0c\u4e00\u76f4\u9000\u5230\u521d\u4e8c\u7684\u5185\u5bb9\u4e0a\uff1a\u201c\u9510\u89d2\u4e09\u89d2\u51fd\u6570\u7684\u5b9a\u7406\u4f60\u77e5\u9053\u5427\uff1f\u201d
\u3000\u3000\u4ed6\u8bf4\uff1a\u201c\u8001\u5e08\uff0c\u4f60\u80fd\u4e0d\u80fd\u8bf4\u5f97\u5177\u4f53\u4e00\u70b9\u513f\uff1f\u201d
\u3000\u3000\u6211\u8bf4\uff1a\u201c\u5728\u4e00\u4e2a\u76f4\u89d2\u4e09\u89d2\u5f62\u91cc\uff0c\u90a3\u4e2asin\u03b1\u7b49\u4e8e\u4ec0\u4e48\uff1f\u201d
\u3000\u3000\u4ed6\u773c\u775b\u4e00\u4eae\uff1a\u201csin\u03b1\u7b49\u4e8e\u5bf9\u8fb9\u6bd4\u659c\u8fb9\u3002\u201d
\u3000\u3000\u6211\u8bf4\uff1a\u201c\u5c31\u662f\u5b83\u3002\u201d\u53c8\u95ee\uff1a\u201ccos\u03b1\u7b49\u4e8e\u4ec0\u4e48\uff1f\u201d
\u3000\u3000\u201ccos\u03b1\u7b49\u4e8e\u90bb\u8fb9\u6bd4\u659c\u8fb9\u3002\u201d
\u3000\u3000\u201ctan\u03b1\u5462\uff1f\u201d
\u3000\u3000\u201c\u7b49\u4e8e\u5bf9\u8fb9\u6bd4\u90bb\u8fb9\u3002\u201d
\u3000\u3000\u6211\u603b\u7b97\u677e\u4e86\u4e00\u53e3\u6c14\uff0c\u8bf4\uff1a\u201c\u5b69\u5b50\u4f60\u592a\u5389\u5bb3\u4e86\uff0c\u4f60\u7adf\u7136\u8fde\u8fd9\u4e2a\u4e1c\u897f\u90fd\u8bb0\u7740\uff0c\u5c31\u4ece\u5b83\u5f00\u59cb\u3002\u201d
\u3000\u3000\u6211\u4e3a\u4e86\u628a\u8fd9\u4e2a\u5b66\u751f\u7684\u95ee\u9898\u89e3\u51b3\uff0c\u4e00\u76f4\u7ed9\u4ed6\u9000\u5230\u521d\u4e8c\u7684\u5185\u5bb9\u4e86\uff0c\u4ece\u521d\u4e8c\u5f00\u59cb\u8bb2\u8d77\u3002
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初二就学高中内容啊
初中主要是锐角三角函数吧
在直角三角形中，这个图片有点大
以角A为例：
正弦（sin）等于对边比斜边；sinA=a/c
余弦（cos）等于邻边比斜边；cosA=b/c
正切（tan）等于对边比邻边；tanA=a/b
主要是这个，这个是需要记住的。
到了高中的话，主要是讲角扩大到了任意角
如图在半径为1的圆中
更确切的说：r = 根号下（x²+y²）
sinΘ = y/r
cosΘ = x/r
tanΘ = y/x
高中三角函数还引入 了弧度制，并且在题目中更多的讲弧度制，弧度制请参考：网页链接
还需要记住诱导公式，请参考网页链接（只需要知道sin cos tan即可），诱导公式主要是将任意角转化成锐角三角函数。
高中还要学习三角恒等变化，请参考网页链接，只需要了解：基础三角恒等式、
两角和与差、二倍角（变形：降幂公式）、Asinα+Bcosα = √(A²+B²)sin[α+Θ] （其中tanΘ = b/a），要求高一点的话积化和差，和差化积也需要掌握
cos(π＋a)=–sina
cos(π＋a)=–cosa
tan(π＋a)=tana
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绛旓細2a=6鈫抋²=9;鈭碽²=9-8=1.鈭寸煭杞撮暱2b=2锛屼笖鐒︾偣寮﹂暱绛変簬鐭酱闀匡紝鏁呬緷鐒︾偣寮﹂暱鍏紡 d=2ab²/(a²-c²cos²胃)寰:2=2脳3脳1²/(9-8cos²胃)瑙ｅ緱锛宑os胃=卤鈭3/2.鏁呭剧瑙: 胃=30掳鎴150掳 琛ュ厖: 鍙湁鎴戞闈㈠洖绛斾簡锛屼絾妤间富閫夌瓟妗...
绛旓細鍥炵瓟锛氳〃绀轰竴鏉＄洿绾垮浜庢í杞寸殑鍊炬枩绋嬪害濡倅=kx+d k鏄枩鐜
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绛旓細鍥炵瓟锛氫綘鏄嚑骞寸骇鐨?
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