Question

Which of the following could be points on the unit circle?
A. (1/2, 2/3)
B. (4/3, 4/5)
C. (6/7, square root of 13/7)
D. (15/13, 12/13)

Answer 1

well the unit circle says

x^2 + y^2 = 1

so substitute the points and see which is true.

Answer 2

The unit circle has center (0,0) and radius 1. You can eliminate all but one of the answers by asking yourself what is the maximum the x or y coordinate of a point on the circle could ever possibly be.

Answer 3

okay thank you