Question 929594
The distance from the center of the circle to the vertex of the triangle (Y) forms a right triangle along with the radius of the circle (R). The other leg of that triangle is 1/2 the length of the equilateral triangle leg, X.
{{{X^2+R^2=Y^2}}}
{{{X^2+8^2=17^2}}}
{{{X^2=289-64}}}
{{{X^2=225}}}
{{{X=15}}}
So the perimeter would be,
{{{P=3(2X)}}}
{{{P=6(15)}}}
{{{P=90}}}{{{cm}}}