Show that the three circular sectors are equal



The three circular sectors have all radius \(1\).
Their central angles add up to \(90^\circ\).
We prove that their central angles are \(30^\circ\).
By the symmetry of the figure, the external circular sectors have the same central angle:
it suffices to show that this angle is \(30^\circ\).
This central angle is complementary to a \(60^\circ\) angle.
Indeed, recall the equilateral triangle from .