Question

Determine for what value of thitha,, 2 cos square thitha - 3 cos thitha +1 = 0

Answer 1

$\underline\bold{\huge{ANSWER \: :}}$



▶HERE, IN THIS ANSWER, I AM HOLDING THE "THETAS" AS "x".

______________________________

2 cos² x - 3 cos x + 1 = 0

=> 2 cos²x - (2+1)cos x + 1 = 0

=> 2 cos²x - 2 cosx - cosx + 1 = 0

=> 2 cos x (cos x - 1) - 1 (cos x - 1) = 0

=> (cos x - 1) (2 cos x - 1) = 0

______________________________

EITHER :

cos x - 1 = 0

=> cos x = 1

=> cos x = cos 0°

=> x = 0°

______________________________

OR :

2 cos x - 1 = 0

=> 2 cos x = 1

=> cos x = 1/2

=> cos x = cos 60°

=> x = 60°

______________________________