Hello, John!
I'm delighted that you solved it.
Here's my approach . . .
We have: .
. . . . . .
. . . . . .
. . . . . .
The maximum value of is 1.
The minimum value of is -1.
Therefore: .
. . . . . . . . . . . . .
PROVE that sin^4 x + cos^4 x= 1/4(3+cos4x). hence find the largest possible value and smallest possible value of sin^4 x+cos^4 x
Brainquicken