7/6π的正弦值和5/6π的余弦值的积是多少
问题描述:
7/6π的正弦值和5/6π的余弦值的积是多少
答
sin7/6pi=sin(pi+1/6pi)=-sin1/6pi=-1/2
cos5/6pi=cos(pi-1/6pi)=-cos1/6pi=-根号3/2
积=根号3/4