The center of a circle is located at (0,4). The endpoint, X, of one of the circle's radii is (-4,-5). Segment XY is a diameter of the circle. Where is point Y located?

Question

A.(13,4)

B.(5,4)

C. (4,5)

D. (4,13)

Answer 1

The opposite end of the diameter XY must be as far to the right of the y-axis as X is to the left, so the x coord of Y must be 4, because X is 4 units to the left (-4), and the centre of the circle is on the y-axis.

The y coord of Y is as far above y=4 as X is below y=4. X is 4-(-5)=9 units below y=4, so Y is 9 units above y=4, so y=13. 

The coords of Y are (4,13), answer D.