Question

if sin theta+costheta=p, then show that p square minus 1 by 2= sintheta×costheata​

Answer 1

p = sin theta + cos theta

p square = sin square theta + cos square theta + 2sintheta.costheta

p square = 1 + 2.sin theta.cos theta

p square - 1 = 2.sin theta.cos theta

p square -1/2 = sin theta.cos theta

the key is,

sin square theta + cos square theta = 1