quantitykind:PlaneAngle
The inclination to each other of two intersecting lines, measured by the arc of a circle intercepted between the two lines forming the angle, the center of the circle being the point of intersection. An acute angle is less than \(90^\circ\), a right angle \(90^\circ\); an obtuse angle, more than \(90^\circ\) but less than \(180^\circ\); a straight angle, \(180^\circ\); a reflex angle, more than \(180^\circ\) but less than \(360^\circ\); a perigon, \(360^\circ\). Any angle not a multiple of \(90^\circ\) is an oblique angle. If the sum of two angles is \(90^\circ\), they are complementary angles; if \(180^\circ\), supplementary angles; if \(360^\circ\), explementary angles.