If `costheta-sintheta=sqrt(2)sintheta` then Prove that `costheta+sintheta=sqrt(2)costheta`

If `costheta-sintheta=sqrt(2)sintheta` then Prove that `costheta+sintheta=sqrt(2)costheta`

To ask Unlimited Maths doubts download Doubtnut from - https://goo.gl/9WZjCW If `costheta-sintheta=sqrt(2)sintheta` then Prove that `costheta+sintheta=sqrt(2)costheta`