Denote the points of intersection of the circles as $A$ and $B$ and the centers as $O_1$ and $O_2$.
In triangle $O_1AO_2$ you have three sides so you can find the angles. Then from the information about the angles and the radii of circles you can find the arc lengths and the perimeter.
Denote the points of intersection of the circles as $A$ and $B$ and the centers as $O_1$ and $O_2$.
In triangle $O_1AO_2$ you have three sides so you can find the angles. Then from the information about the angles and the radii of circles you can find the arc lengths and the perimeter.