Circle Areas

Geometry Level 2

Two circles with radius 6 6 pass through each other's centers. What is the area of the white region?

36 π 3 36\pi\sqrt{3} 48 π + 18 3 48\pi + 18\sqrt{3} 196 196 72 π 72\pi Cannot be determined

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2 solutions

The white region is equal to two two-third circle with radius 6 6 plus two equilateral triangles with side length 6 6 . Therefore the area is:

A = 2 × 2 3 × 6 2 π + 2 × 6 2 sin 6 0 2 = 48 π + 18 3 A = 2 \times \frac 23 \times 6^2 \pi + 2 \times \frac {6^2\sin 60^\circ} 2 = \boxed{48\pi + 18\sqrt 3}

The required area is

2 π r 2 2 ( 1 2 × r 2 × 2 π 3 r 2 3 4 ) 2πr^2-2\left (\dfrac 12\times r^2\times \dfrac {2π}{3}-\dfrac {r^2\sqrt 3}{4}\right ) ,

where r = 6 r=6 is the radius of each circle.

So, the required area is

4 π r 2 3 + r 2 3 2 \dfrac {4πr^2}{3}+\dfrac {r^2\sqrt 3}{2}

= 48 π + 18 3 =\boxed {48π+18\sqrt 3} .

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