, what is the area of the shaded region in rounded to the nearest integer?
Three identical circles which are externally tangent to each other are inscribed in an equilateral triangle as shown. Given that the the radius of each circle is
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Relevant wiki: Area of Triangles - Problem Solving - Easy
Consider my figure.
tan 3 0 = x 3 ⟹ x = tan 3 0 3
It follows that A C = 2 ( tan 3 0 3 ) + 6 = tan 3 0 6 + 6 .
The area of an equilateral triangle is given by A = 4 3 a 2 where a is the side length. The area of a circle is given by A = π r 2 where r is the radius.
From the figure, the area of the shaded region is equal to the area of the equilateral triangle minus the area of the three circles.
Thus,
A s h a d e d = 4 3 ( tan 3 0 6 + 6 ) 2 − 3 ( π ) ( 3 2 ) ≈ 3 2 cm 2 .