Question

The chord of a circle of radius 10 cm subtends a right angle at its centre. The length of the chord (in cm) is [CBSE 2014]
(a) $\frac{5}{\sqrt{2}}$ cm
(b) $5\sqrt{2}$ cm
(c) $10\sqrt{2}$ cm
(d) $10\sqrt{3}$ cm

Answer 1

In right triangle AOB
By using Pythagoras theorem, we have
AB² = BO² + OA²
= 10² + 10²
= 100 + 100
= 200
∴OR² = 200
⇒OR = $10\sqrt{2}$ cm
Hence, the correct answer is option (c).