Word Origin & History. epicene mid-15c., originally a grammatical term for nouns that may denote either gender, from L. epicoenus common, from Gk. Extended sense of characteristic of both sexes first recorded in English c.1600; that of effeminate 1630s.
A parallelogram is a quadrilateral with two pairs of parallel sides. Equivalent conditions are that opposite sides are of equal length; that opposite angles are equal; or that the diagonals bisect each other. Parallelograms also include the square, rectangle, rhombus and rhomboid. Rectangle: all four angles are right angles. 2  An equivalent condition is that the diagonals bisect each other and are equal in length. 3  Informally: a box or oblong (including a square). 4  Square (regular quadrilateral): all four sides are of equal length (equilateral), and all four angles are right angles.
Right-Angled Triangles. A right-angled triangle (also called a right triangle) is a triangle with a right angle (90Â°) in it. The right angled triangle is one of the most useful shapes in all of mathematics! (It is used in the Pythagoras Theorem and Sine, Cosine and Tangent for example). Try it yourself (drag the points): Two Types. There are two types of right angled triangle: Isosceles right-angled triangle. One right angle Two other equal angles always of 45Â° Two equal sides . Scalene right-angled triangle. One right angle Two other unequal angles No equal sides