2019 · Q87
Two equal circles intersect such that each passes through the centre of the other. If the length of the common chord of the circles is 10√3 cm, then what is the diameter of the circle?
Elementary MathematicsCircles
- A10 cm
- B15 cm
- C20 cm
- D30 cm
Explanation
The centres are r apart and the common chord bisects the line of centres, so (r/2)^2 + (5√3)^2 = r^2 gives 75 = 3r^2/4, r = 10 cm, diameter 20 cm.