Question

已知cosa=3/5,且a为锐角，则sin(a+π/6)=? 求具体步骤

Answer 1

你好！cosa=3/5，且α为锐角
所以：sina＞0
所以：sina=√(1--cos^2a)=4/5
所以：sin（a+π/6)=sinacosπ/6+cosasinπ/6
-=4/5x√3/2+3/5x1/2
=(4√3+3)/10

Answer 2

a是锐角则sina>0
因为sin�0�5a+cos�0�5a=1
cosa=3/5
所以sina=4/5
sin(a+π/6)
=sinacosπ/6+cosasinπ/6
=4/5*√3/2+3/5*1/2
=2√3/5+3/10