The Pythagorean trigonometric identity is a trigonometric identity expressing the Pythagorean theorem in terms of trigonometric functions. Along with the sum-of-angles formulae, it is one of the basic relations between the sine and cosine functions, from which all others may be derived. Statement of the identity Mathematically, the Pythagorean identity states: :\sin^2 \theta + \cos^2 \theta = 1.\! (Note that means . This relation between sine and cosine is sometimes called the fundamental Pythagorean trigonometric identity. If the length of the hypotenuse of a right triangle is ...

The Twenty-fourth Amendment (Amendment XXIV) prohibits both Congress and the states from conditioning the right to vote in federal elections on payment of a poll tax or other types of tax. The amendment was proposed by Congress to the states on August 27, 1962, and was ratified by the states on January 23, 1964. Poll taxes appeared in southern states after Reconstruction as a measure to prevent African Americans from voting, and had been held to be constitutional by the Supreme Court of the United States in the 1937 decision Breedlove v. Suttles. At the time of this amendment's passage,...