IKMC 2019 - Grades 9-10 - Set 2 - Self-study Question 17

Question 17

The pictured shape is made from three equal circles of radius R with collinear centres. The middle circle passes through the other two centres. What is the perimeter of the outer shape?

Question illustration

$10\pi R/3$
$5\pi R/3$
$2\pi R\sqrt3/3$
$2\pi R\sqrt3$
$4\pi R$