Question

If cos 2x + 2 cos r = 1, then (sin’x) (2 - cos? c) is equal to​

Answer 1

Given,

cos 2x + 2 cos x = 1

To Find

The Value of sin^2x ( 2 - cos^2x )

Solution,

1) we will use the approach of the hit and trial to solve this question that would be the easy one.

2) we will guess the value of the x for which the cos2 x + 2cosx = 1 satisfies this equation.

3) Let take the value of x is 90°

• cos180°+ 2cos90°
• 1 + 2 × 0
• 1

1 is equal to RHS.

4) Now put this value of of in given equation and find the value.

• sin²x (2-cos²x)
• sin²90° (2-cos²90°)
• 1 ( 2 - 0 )
• 2

sin²x ( 2 - cos²x ) = 2