Question

the diagram on the right shows a circle with centre O . Line OP is perpendicular to chord MN . The length of line OP is 3 cm an the length of chord MN is 7 cm. Find the circumference of the circle .
[Use π = 3.142]

Answer 1

First, you find the radius.

Since MN = 7; MP = 7÷2 = 3.5

Then, draw line from O to M and use Pythagoras' Theorem to solve

$x {}^{2} = {3.5}^{2} + {3}^{2}$
$x = 4.609772229$

Circumference is 2 × pi × radius
You found your radius, so substitute.

2 × 3.142 × 4.609772229= 28.96780868

Correct the answer to how many significant figures the question wants. Hopefully this helps :D