Question

If the length of a chord of a circle is 16 cm and is at a distance of 15 cm from the centre of the circle, then the radius of the circle (in cm) is :

• A. 15
• B. 16
• C. 17
• D. 34

Answer 1

The correct option is C

17

Draw OL $\perp$ chord AB. Join OA.

Let OA = r. Then,

AL = $\frac{AB}{2}$ = 8 cm and OL = 15 cm

Now, ${OA}^2$ = ${AL}^2$ + ${OL}^2$

$r^2$ = $8^2$ + ${15}^2$ = 289 ${cm}^2$

Therefore r = 17 cm