A piece of paper in the shape of an equilateral triangle with side length 3 and a circular piece of paper with radius 1 are glued together so that their centers coincide. How long is the outer perimeter of the resulting 2-dimensional shape?
See the image here :
AE = 1 = FB
And minor arc EF = 2 pi (1) / 6 = pi/ 3
So....by symmetry.....the perimeter is
3 [ 2 + pi / 3) ] =
[ 6 + pi ] units ≈ 9.14 units