Special right triangle is 90°, leaving the remaining angle to be 30°. Right triangles whose sides are of integer lengths, with the sides collectively known as Pythagorean triples, possess angles that cannot all be rational numbers of degrees. (This follows from Niven's theorem.) They are most useful in that they may be easily remembered and any multiple of the sides produces the same relationship. Using Euclid's formula for generating Pythagorean triples, the sides must be in the ratio where "m" and "n" are any positive integers such that . There are several Pythagorean triples which are well-known, including those with sides in the
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