Question

Sin 45 cos 65+sin135 cos 115=?​

Answer 1

sin 45 cos 65 + sin 135 cos 115

= sin 45 cos 65 + sin (180-45) cos (180-115)

= sin 45 cos 65 - sin 45 cos 65 (sin (180-A)= sin A and cos(180-A) = -cos A)

= 0