Special right triangle allows one to quickly calculate various lengths in geometric problems without resorting to more advanced methods. "Angle-based" special right triangles are specified by the relationships of the angles of which the triangle is composed. The angles of these triangles are such that the larger (right) angle, which is 90 degrees or radians, is equal to the sum of the other two angles. The side lengths are generally deduced from the basis of the unit circle or other geometric methods. This approach may be used to rapidly reproduce the values of trigonometric functions for the angles 30°, 45°, and 60°. Special
Pressure angle force along the pitch line which is responsible for power transmission is proportional to the cosine of pressure angle. The one which exerts thrust (perpendicular to the pitch line) is proportional to the sine of pressure angle. So it is advised to keep the pressure angle low. Standard pressure angles are 14.5 and 20 degrees. Just as there are three types of profile angle, there are three types of corresponding pressure angle: the transverse pressure angle, the normal pressure angle, and the axial pressure angle. Pressure angle Pressure angle in relation to gear teeth, also known as the angle of