Question

Cos theta + sin theta square equal to 1 + sin 2 theta what is answer

Answer 1

This result follows almost directly from the following:

(a+b)2=a2+2ab+b2

sin2(x)+cos2(x)=1

sin(2x)=2sin(x)cos(x)

With these, we have

(sin(x)+cos(x))2=sin2(x)+2sin(x)cos(x)+cos2(x)

=(sin2(x)+cos2(x))+2sin(x)cos(x)

=1+sin(2x)