Question

7

A chord of a circle is 18 cm long. It is
6.3 cm from the centre of the circle
Calculate the radius of the circle to the
nearest whole number. step by step show the calculation​

Answer 1

11 cm

Explanation:

r² = 9² + 6.3²

r² = 120.69

r = 10.9859000542

Rounded

r = 11 cm

Answer 2

`\rm 10.9 cm`

Explanation:

Given that :-

• A chord of a circle is 18 cm long.
• It is 6.3 cm from the centre of the circle.

And we need to find out the radius of the circle.

`\text{ Theorem :-}`

• Perpendicular from the centre of circle , to the chord , bisects the chord .

Using Pythagoras Theorem :-

`\implies \rm OA^2= AB^2+OB^2\\\\\rm\implies OA^2= (6.3 cm)^3+(9cm)^2\\\\\rm\implies OA^2=</p><p>120.69 \\\\\implies\boxed{\rm OA = 10.9 cm }`

Hence the radius is 10.9 cm