Question No. 3

Lesson#5
Question No. 3
Q3:Prove the following:
(i): sin(180° + α) sin⁡(90°−α)=−sin α cos α
(ii): ⁡sin⁡780° sin480° +cos⁡120° sin 30°=1/2
(iv): cos⁡330° sin⁡600°+ cos⁡120° sin⁡150°=−1
(iii): ⁡cos 306°+cos 234°+cos 162°+cos 18°=0
Trigonometric Identities
Chapter No 10
Exercise No 10.1
Mathematics
part 1