Question

if 2 sin2thita-cos2thita = 2,then find the value of thita.

Answer 1

2 sin^2 A - cos^2 A = 2

2 sin^2 - ( - 2 cos^2 A + 3 cos^2 A ) = 2

2 sin^2 + 2 cos^A - 3 cos^2 A = 2

2( sin^2 A + cos^2 A ) - 3 cos^2 A = 2

2 ( 1 ) - 3 cos^2 A = 2

2 - 3 cos^2 A = 2

- 3 cos^2 A = 0

3 cos^2 A = 0

cos^2 A = 0

cos A = 0

cos A = 90°

Therefore the value of theta is 90°

Answer 2

2 sin² A - cos² A = 2

2 sin²A - ( 1 - sin² A ) = 2

2 sin² A - 1 + sin²A = 2

3 sin²A = 2 + 1

3 sin² A = 3

sin²A = 3 / 3

sin²A = 1

sin A = 1

sinA = sin 90°

A = 90°


$\:$


Therefore, value of theta is 90°