Question

prove that 1/sec 2theta = cos^4 - sin ^4​

Answer 1

Step-by-step explanation:

LHS =cos

4

θ−sin

4

θ

=(cos

2

θ−sin

2

θ)(cos

2

θ+sin

2

θ)

=(cos

2

θ−sin

2

θ)(1)

=cos2θ

⇒ LHS = RHS

Hence proved