sin12分之5派等于多少cos12分之5派得多少.
问题描述：
sin12分之5派等于多少cos12分之5派得多少.
答
0·022844319 0·999739034
答
sin 5/12π
=sin(1/6π +1/4π)
=sin(1/6π)cos(1/4π) + cos(1/6π)sin(1/4π)
=√2/2*1/2 + √2/2*√3/2
=(√2+√6)/4
cos 5/12π
=cos(1/6π +1/4π)
=cos(1/6π)cos(1/4π) — sin(1/6π)sin(1/4π)
=√3/2*√2/2 — 1/2 *√2/2
=(√6 — √2)/4