正弦与余弦怎样转换 三角函数正弦和余弦的转换公式？
\u4e09\u89d2\u51fd\u6570\u6b63\u5f26\u548c\u4f59\u5f26\u7684\u8f6c\u6362\u516c\u5f0f\uff1fsin\uff08pi/2-a\uff09=cosa\u662f\u8fd9\u6837\u6765\u7684
\u6839\u636esin(A-B)=sinAcosB-cosAsinB
\u6240\u4ee5sin\uff08\u03c0/2-a\uff09=sin\u03c0/2cosa-cos\u03c0/2sinB
\u56e0\u4e3asin\u03c0/2=1
cos\u03c0/2=0
\u6240\u4ee5sin\uff08\u03c0/2-a\uff09=cosa
\u6b64\u5916\u8fd8\u6709\u516c\u5f0f\uff0c
sin\uff08\u03c0/2\uff0b\u03b1\uff09\uff1dcos\u03b1\uff08k\u2208Z\uff09
cos\uff08\u03c0/2\uff0b\u03b1\uff09\uff1d\uff0dsin\u03b1\uff08k\u2208Z\uff09
tan\uff08\u03c0/2\uff0b\u03b1\uff09\uff1d\uff0dcot\u03b1\uff08k\u2208Z\uff09
cot\uff08\u03c0/2\uff0b\u03b1\uff09\uff1d\uff0dtan\u03b1\uff08k\u2208Z\uff09
sin\uff08\u03c0/2\uff0d\u03b1\uff09\uff1dcos\u03b1\uff08k\u2208Z\uff09
cos\uff08\u03c0/2\uff0d\u03b1\uff09\uff1dsin\u03b1\uff08k\u2208Z\uff09
tan\uff08\u03c0/2\uff0d\u03b1\uff09\uff1dcot\u03b1\uff08k\u2208Z\uff09
cot\uff08\u03c0/2\uff0d\u03b1\uff09\uff1dtan\u03b1\uff08k\u2208Z\uff09
sin\uff083\u03c0/2\uff0b\u03b1\uff09\uff1d\uff0dcos\u03b1\uff08k\u2208Z\uff09
cos\uff083\u03c0/2\uff0b\u03b1\uff09\uff1dsin\u03b1\uff08k\u2208Z\uff09
tan\uff083\u03c0/2\uff0b\u03b1\uff09\uff1d\uff0dcot\u03b1\uff08k\u2208Z\uff09
cot\uff083\u03c0/2\uff0b\u03b1\uff09\uff1d\uff0dtan\u03b1\uff08k\u2208Z\uff09
sin\uff083\u03c0/2\uff0d\u03b1\uff09\uff1d\uff0dcos\u03b1\uff08k\u2208Z\uff09
cos\uff083\u03c0/2\uff0d\u03b1\uff09\uff1d\uff0dsin\u03b1\uff08k\u2208Z\uff09
tan\uff083\u03c0/2\uff0d\u03b1\uff09\uff1dcot\u03b1\uff08k\u2208Z\uff09
cot\uff083\u03c0/2\uff0d\u03b1\uff09\uff1dtan\u03b1\uff08k\u2208Z\uff09
\u8fd9\u5199\u516c\u5f0f\u53eb\u505a\u8bf1\u5bfc\u516c\u5f0f\uff0c\u4e0d\u8981\u6b7b\u8bb0
\u65b9\u6b63\u524d\u9762\u62ec\u53f7\u91cc\u7684\u6709k\u03c0/2
(k\u4e3a\u975e\u96f6\u6b63\u6570)\u7684\u5f62\u5f0f\u65f6
\u4e09\u89d2\u51fd\u6570\u540d\u5c31\u8981\u53d8
\u4e5f\u5c31\u662fsin
\u53d8
cos
cos\u53d8
sin
tan\u53d8cot
cot\u53d8tan
\u800c\u7b26\u53f7\u662f\u8fd9\u6837\u786e\u5b9a\u7684\u5047\u8bbea=\u03c0/6
\u4ee5cos\uff08\u03c0/2\uff0b\u03b1\uff09\uff1d\uff0dsin\u03b1\u4e3a\u4f8b
\u628acos\uff08\u03c0/2\uff0b\u03b1\uff09=cos\uff08\u03c0/2\uff0b\u03c0/6\uff09=cos2\u03c0/3<0
\u6240\u4ee5\u540e\u9762\u7684\u7b26\u53f7\u662f-,\u90a3\u4e48cos\uff08\u03c0/2\uff0b\u03b1\uff09=-sina
1，利用诱导公式
sin(α+π/2)=cosα
sin(α+3π/2)=-cosα
2，利用半角公式
sinα=±√[(1-cos2α)/2]
3，利用sin²α+cos²α=1
1，利用诱导公式
sin(α+π/2)=cosα
sin(α+3π/2)=-cosα
2，利用半角公式
sinα=±√[(1-cos2α)/2]
3，利用sin²α+cos²α=1
余弦＝正弦／正切
余弦=±✔1一正弦的平方
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