Mathematics

Mathematics

Problem

In a circle of radius 10 cm10\,\text{cm}, the length of chord PQPQ is 12 cm12\,\text{cm}. What is the distance of the chord from the centre of the circle? a) 4 cm4\,\text{cm} b) 6 cm6\,\text{cm} c) 8 cm8\,\text{cm} d) 6.6 cm6.6\,\text{cm}
Intuitive explanation

The key insight is that the perpendicular from the center of a circle to a chord always bisects that chord, creating a right triangle you can solve. Once you drop a perpendicular from the center to the chord, you'll have the radius as the hypotenuse, half the chord length as one leg, and the distance you're looking for as the other leg—then just apply the Pythagorean theorem.

Intuitive explanation

The key insight is that the perpendicular from the center of a circle to a chord always bisects that chord, creating a right triangle you can solve. Once you drop a perpendicular from the center to the chord, you'll have the radius as the hypotenuse, half the chord length as one leg, and the distance you're looking for as the other leg—then just apply the Pythagorean theorem.

Browse the problem library