Question 869777
Let x = 2t
Then we can write the expression as
y = 1 + 4cos(x) - 4sin(2x)
y = 1 implies 4cos(x) - 4sin(2x) = 0
Divide through by 4 and replace sin(2x) with 2sin(x)cos(x):
cos(x) - 2sin(x)cos(x) = 0
Factor:
cos(x)(1 - 2sin(x)) = 0
This gives cos(x) = 0, or sin(x) = 1/2
I'll let you take it from here (don't forget x=2t)