The Reuleaux triangle is the shape formed by the intersection of three circles, with each circle passing through the others' centers. Regardless of rotation, a Reuleaux triangle's width will always equal the radius of the circles:
Image: Wolfram MathWorld
Write a program that takes a width
r as input and displays a Reuleaux triangle of that width (in pixels).
You must display the shape in isolation, i.e. solid-filled, un-stroked, and over a solid-filled background.
code-golf - Shortest program in bytes wins.