Question #b5658

1 Answer
May 25, 2017

See Below.

Explanation:

Identities Required:
sin(2x)=2sin(x)cos(x)

sin2(x)+cos2(x)=1
sin2(x)=1cos2(x)

cos(2x)=cos2(x)sin2(x)=cos2(x)(1cos2(x))=2cos2(x)1

Now solving:
sin(2x)sin(x)cos(2x)cos(x)=sec(x)
2sin(x)cos(x)sin(x)2cos2(x)1cos(x)=RHS
2cos(x)2cos(x)+1cos(x)=RHS
sec(x)=RHS
QED