In a circle with center O, AC is a chord. OB is perpendicular to AC at point B. If OA = 15 cm and AC = 24 cm, what is the length of OB?
Show answer & explanation
Correct answer: A
Explanation
Given:
OA = 15 cm
AC = 24 cm
OB ⟂ AC
The perpendicular drawn from the center to the chord bisects the chord.
AB = AC/2
OB² + AB² = OA²
AB = 24/2 = 12
OB² + 12² = 15²
OB² + 144 = 225
OB² = 81
OB = 9 cm