Question

plz solve this question.....​

Answer 1

Answer:

Step-by-step explanation:

brainliest please

Answer 2

Heya!!

let
x = theta


we know that

Cos 2x = 2 Cos² x - 1 .... Equation ( i )

=>

2 Cos x = ( x +1/x ) { Given }

SQUARING BOTH SIDE'S WE GET

4 Cos² x = x² + 1/x² + 2(x)×(1/x )

Becoz ( a + b )² = a² + b² + 2ab

=>

4 Cos² x = x² + 1/x² + 2

=>

2 Cos² x = 1/2 { x² + 1/x² + 2 }

Now, put this value of 2 Cos² x in Equation ( i ) we get

Cos 2x = 1/2 { x² + 1/x² + 2 } -1

=>

Cos 2x = 1/2 { x² + 1/x² } + 0

=>

Cos² 2x = 1/2 { x² + 1/x² }