2021 · Q16
Let PAB be a secant to a circle intersecting the circle at A and B. Let PT be the tangent segment. If PA = 9 cm and PT = 12 cm, then what is AB equal to?
Elementary MathematicsCircles
- A5 cm
- B6 cm
- C7 cm
- D9 cm
Explanation
By the tangent–secant theorem, PT² = PA · PB. So 144 = 9 · PB, giving PB = 16 cm. Then AB = PB − PA = 16 − 9 = 7 cm. Hence option C.