Answer: 45 degrees or pi/4 radians
Step-by-step explanation:
I recommend using the unit circle for this. You're looking for a point (x,y) on the unit circle such that x = y.
In the first quadrant Q1, this happens when theta = 45 degrees = pi/4 radians.
Another instance is in Q3 when theta = 225 degrees = 5pi/4 radians.