2020 · Q70
In a circle of radius 5 cm, AB and AC are two chords such that AB = AC = 8 cm. What is the length of chord BC?
Elementary MathematicsCircles
- A9 cm
- B9.2 cm
- C9.6 cm
- D9.8 cm
Explanation
Let M be the midpoint of BC and AM = h. Then MB² = 64 − h² and OB² = (5 − h)² + 64 − h² = 25 gives 89 − 10h = 25, so h = 6.4. Then MB² = 23.04, MB = 4.8 and BC = 9.6 cm.