问一道数学题 sin(-1320)乘以cos1110+cos(-1020)乘以sin720,最后再加上tan495,等于?
问题描述:
问一道数学题 sin(-1320)乘以cos1110+cos(-1020)乘以sin720,最后再加上tan495,等于?
答
sin(-1320)cos1110+cos(-1020)sin720+tg495=sin(-1320+360x4)cos(1110-360x3)+cos(-1020+360x3)sin(720-360x2)+tg(495-360)=sin120cos30+0+tg135=sin60cos30-1=3/4-1=-1/4