## sasogeek 5 years ago Show that 1 + Sin2A = (CosA + SinA)^2

1. anonymous

I'll play around with the left side and try to get it to look like the right side.$1 + \sin2A = \sin^2A+\cos^2A+2\sin A \cos A$$=\cos^2A+2\sin A \cos A +\sin^2A$ If we think of sinA as being a and cosA as being b, then the above expression is equivalent to a^2 + 2ab+ b^2, this is the same as the square of the sum a + b... so.... $\cos^2A+2 \sin A \cos A+\sin^2A = (\cos A+\sin A)^2$

2. sasogeek

thanks for the response :) I tried to work that out but i got stuck after expanding the first step. thanks again :)