Question

let cosA = cos54 then a/2
​

Answer 1

=> cosA = cos54 then A=54

=> A/2 = 54/2 = 27

therefore the answer is 27

I think this is the answer.....I hope this helps u

Answer 2

Here is your answer:-

Let A = 18°

Therefore, 5A = 90°

⇒ 2A + 3A = 90˚

⇒ 2θ = 90˚ - 3A

Taking sine on both sides, we get

sin 2A = sin (90˚ - 3A) = cos 3A

⇒ 2 sin A cos A = 4 cos3
3
A - 3 cos A

⇒ 2 sin A cos A - 4 cos3
3
A + 3 cos A = 0

⇒ cos A (2 sin A - 4 cos2
2
A + 3) = 0

Hope it help you

Plz mark me as Brainlist