Triangles Mike S Math Page Let C = 90 ∘ The legs ( a and b) are given by the following equations a = c sin A b = c cos A We want to find the ratio a b a b = c sin A c cos A = sin A cos A = tan ( A) Now substitute the value of A in your example You can either use 15 ∘ or 75 ∘ (using one() Triangle Word Detail A right triangle with an inside angle of 15 ° is called a right triangle The long perpendicular edge is times the short perpendicular edgeThe most important feature of the triangle (15 °, 75 °, 90 °) is as follows The perpendicular height to the hypotenuse is onefourth of the hypotenuse leight To make the proof, 15-75-90 triangle theorem