Question

Cos"4 A-sin4 A= 2cos"2A
​

Answer 1

Step-by-step explanation:

LHS=sin

4

x+cos

4

x

=(sin

2

x)

2

+cos

4

x

=(1−cos

2

x)

2

+cos

4

x

=1+cos

4

x−2cos

2

x+cos

4

x

=1−2cos

2

x+2cos

4

x