Three identical circles are inscribed within an equilateral triangle, as shown above. If each of the radii of the circles is 3, what is the perimeter of the triangle?A. 18(1+√3)
B. 9(1+2√3)
C. 18√3
D. 9(1+√3)
E. 6(1+√3)
See attached file:
Attachment:
Triangle.PNG
Side of this equilateral triangle equals to
2r (middle part) + 2AB. Now, AB is a leg opposite 60 degrees in 30-60-90 right triangle. Sides in 30-60-90 right triangle are in the ration \(1:\sqrt{3}:2\), so \(AB=r\sqrt{3}\)
So you can see that: side equals to \(2r+2*(r\sqrt{3})=6+6\sqrt{3}\), so \(P=3*(6+6\sqrt{3})=18(1+\sqrt{3})\).
Answer: A.
I am wondering here why 4 x (3√3) <--- side of one triangle wouldn't give us the same result.