Question

sin270 sin 50 + cos 0 cos 40=???

Answer 1

Sin270 sin 50 + cos 0 cos 40= -1 * sin 50 + 1* cos 40 =
(sin50 = cos 40)
=-cos40 + cos40 = 0

Answer 2

sin270 sin 50 + cos 0 cos 40=?
sin270=-1. cos 0=1.
cos 40= sin(90°- 50°)= sin 50.
- sin 50 + cos 40=
- - sin 50 + sin 50=0.