The number of real solutions of the equation \({\cos ^7}x + {\sin ^4}x - 1 = 0\) in the interval [-π, π] is:

The number of real solutions of the equation \({\cos ^7}x + {\sin ^4}

1.	The number of real solutions of the equation \({\cos ^7}x + {\sin ^4}x - 1 = 0\) in the interval [-π, π] is:
A.	1
B.	3
C.	4
D.	7
Answer» C. 4