Reinforced rubber reinforcement structure are placed under angles larger than 54.7 angular degrees, the fibres want to relocate to their optimal path when pressurized. This means that the fibres will re-orient themselves until they have reached their force equilibrium. In this case this will lead to an increase in length and a decrease in diameter. With angles smaller than 54.7 degrees the opposite will occur. A product which makes use of this principle is a pneumatic muscle. For a cylinder with a constant diameter the reinforcement angle is constant as well and is 54.7º. This also known as the magic angle or
Degrees of freedom (statistics) independent pieces of information that go into the estimate of a parameter are called the degrees of freedom. In general, the degrees of freedom of an estimate of a parameter are equal to the number of independent scores that go into the estimate minus the number of parameters used as intermediate steps in the estimation of the parameter itself (most of the time the sample variance has "N" − 1 degrees of freedom, since it is computed from "N" random scores minus the only 1 parameter estimated as intermediate step, which is the sample mean). Mathematically, degrees of freedom is