At what two points on the unit circle is the x-coordinate equal to the y-coordinate?
Hint:Use the equation for the unit circle (x^2+y^2=1) but this time, replace y with x.
so you would get
x^2 + x^2 = 1
2x^2 = 1
x^2 = 1/2 or
x = 1/±√2 or √2/2 after rationalized
then y = √2/2
so the two points would be
(√2/2,√2/2) and (-√2/2,-√2/2)