Question

If Cos x – Sin x = √2 Sin x, find the value of Cos x + Sin x:
√2 Cos x
√2 Cosec x
√2 Sec x
√2 Sin x Cos x

Answer 1

(a+b)²= a²+b²+2ab

(a-b)²=a²+b²-2ab

on sub we get (a+b)²-(a-b)²=4ab

now put a= sinx ; b=cosx to get ans