Question

Cos^4a - sin^4 A = cos 2 A​

Answer 1

Answer:

cos

4

A−cos

2

A=sin

4

A−sin

2

A

LHS.

=cos

2

A(1−cos

2

A)

=cos

2

Asin

2

A[∵sin

2

A+cos

2

A=1]

RHS

=sin

2

A(1−sin

2

A)

=sin

2

Acos

2

A[∵sin

2

A+cos

2

A=1]

=cos

2

Asin

2

A

LHS=RHS