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# In the diagram, the two circles have a common centre O. If the area of the large...

### Question

In the diagram, the two circles have a common centre O. If the area of the larger circle is 100$$\pi$$ and that of the smaller circle is 49$$\pi$$, find x

A) 2

B) 3

C) 4

D) 6

### Explanation:

area of larger circle = 100$$\pi$$

$$\pi r^2 = 100\pi$$

R2 = 100

Area of smaller circle = $$49 \pi$$

$$\pi r^2 = 49\pi$$

r2 = 49

Since R = x + r

x = R - r

x = 10 - 7 = 3

## Dicussion (1)

• area of larger circle = 100$$\pi$$

$$\pi r^2 = 100\pi$$

R2 = 100

Area of smaller circle = $$49 \pi$$

$$\pi r^2 = 49\pi$$

r2 = 49