prove cos570 sin510 + sin(-330) cos(-390) = 0
Answers
Answered by
22
cos570=cos570-360=cos210=cos360-210=cos150=cos 180-30=-cos30=-√3/2
sin510=sin510-360=sin150=sin180-30=sin30=1/2
sin -330=sin360-330=sin30=1/2
cos-390=cos360-390=cos-30=cos30=√3/2
therefore, -√3/2*1/2+1/2*√3/2=-√3/4+√3/4=0
hence Proved
sin510=sin510-360=sin150=sin180-30=sin30=1/2
sin -330=sin360-330=sin30=1/2
cos-390=cos360-390=cos-30=cos30=√3/2
therefore, -√3/2*1/2+1/2*√3/2=-√3/4+√3/4=0
hence Proved
Similar questions