Triangle of these conditions hold: (a) each of the angles is positive, and (b) the angles sum to 180°. If degenerate triangles are permitted, angles of 0° are permitted. Three positive angles "α", "β", and "γ", each of them less than 180°, are the angles of a triangle if and only if any one of the following conditions holds: the last equality applying only if none of the angles is 90° (so the tangent function's value is always finite). There are thousands of different constructions that find a special point associated with (and often inside) a triangle, satisfying some unique property:
Zero degrees of freedom Zero degrees of freedom In statistics, the non-central chi-squared distribution with zero degrees of freedom can be used in testing the null hypothesis that a sample is from a uniform distribution on the interval (0, 1). This distribution was introduced by Andrew F. Siegel in 1979. The chi-squared distribution with "n" degrees of freedom is the probability distribution of the sum where However, if and formula_4 are independent, then the sum of squares above has a non-central chi-squared distribution with "n" degrees of freedom and "noncentrality parameter" It is trivial that a "central" chi-square distribution with zero degrees of freedom