Question

if cos 2x+2 cos x=1 then sin²x(2-cos²x) is equal to​

Answer 1

Step-by-step explanation:

cos2x+2cosx=1, x satisfies this equation.

let take the value of x is 90°

cos180°+2cos90°

1 + 2×0

1

equal to RHS

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

sin²x (2-cos²x)

sin²90° (2-cos²90°)

1(2 - 0)

2

sin²x (2-cos²x)=2