Question

Just need question # 12. Thanks

Answer 1

There are two lines from the center of the circle labeled 5.

The lines at 90 degrees from the 5 are chords.  Because both lines are the same distance from the center they are the same length.

The one on the top is labeled as 9, so the line on the bottom is also 9 units long.

X is half the length, so would b 9 /2 = 4.5 units long.