Question

the value of k, for which (cos x + sin x)² + k sin x cos x -1 = 0 is an identity is ​

Answer 1

Answer:

-2

Step-by-step explanation:

Expand the square

$cos {}^{2} x + sin {}^{2} x + 2 \sin(x) \cos(x) + k \sin(x) \cos(x) - 1$

So

$sin {}^{2} \alpha + cos {}^{2} \alpha = 1$

Take 2 and k common

(2+k)=0

k=-2