Question

Prove each of the following identitie
40
1. sino - cos 0 = 1 - 2 cos20​

Answer 1

Answer:

Prove that

(i) sin 80∘cos 20∘− cos 80∘ sin 20∘=3–√2

(ii) cos 45∘ cos 15∘− sin 45∘ sin 15∘=12

(iii) cos 75∘ cos 15∘+ sin 75∘ sin 152=12

(iv) sin 40∘ cos 20∘ + cos 40∘ sin 20∘=3–√2

(v) cos 130∘ cos 40∘l+ sin 130∘ sin 40∘=0