Carcass wrote:
If a circle of radius length 4 and an equilateral triangle of side 4 are made to overlap as shown, what is the approximate area of the shaded region?
A. 1
B. 2
C. 4
D. 8
E. 16
Since the radius has length 4, and the triangle has sides of length 4, we can see we have the following equilateral triangle in our diagram:
Since we have an equilateral triangle, each angle inside the triangle must be
60° as follows:
Now we'll find the area of the green sector below:
Area of sector \(=(\frac{60}{360})(\pi)(4^2)\)
\(=(\frac{1}{6})(\pi)(16)\)
Now we'll find the area of the red equilateral triangle below
We'll use the formula for the area of an equilateral triangle: Area \(= (\frac{\sqrt{3}}{4})(side^2)\)
\(= (\frac{\sqrt{3}}{4})(4^2)\)
\(= (\frac{\sqrt{3}}{4})(16)\)
\(= 4\sqrt{3}\)
The area of the shaded region = (area of green sector) - (area of red equilateral triangle)
\(=(\frac{1}{6})(\pi)(16)-4\sqrt{3}\)
\(≈1.45\)
A is closest.
Answer: A