Question #d1e3c

1 Answer
Dec 4, 2016

Put on a common denominator and use the identity secθ=1cosθ.

(1+sinx)(1+sinx)cosx(1+sinx)+cos2xcosx(1+sinx)=2cosx

Use the identity sin2θ+cos2θ=1.

1+2sinx+sin2x+cos2xcosx+cosxsinx=2cosx

1+2sinx+1cosx+cosxsinx=2cosx

2+2sinxcosx+cosxsinx=2cosx

2(1+sinx)cosx(1+sinx)=2cosx

2cosx=2cosx

Hopefully this helps!