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E

Elevation

1. The vertical height of a point above a base (line or plane).

2. The angle of elevation from one point A to another point B is the angle between the line AB and the horizontal line through A.


Enlargement

A transformation of the plane in which lengths are multiplied whilst directions and angles are preserved. A centre and a positive scale factor are used to specify an enlargement. The scale factor is the ratio of the distance of any transformed point from the centre to its distance from the centre prior to the transformation. Any figure and its image under enlargement are 'similar' - having the same internal angles and ratios between the length of its sides.


Equal

Symbol: =. Read as 'is equal to' or 'equals'. Having the same value. Example: 7 -  2 = 4 + 1 since both expressions, 7 - 2 and 4 + 1 have the same value, 5.

The equals sign combines the two expressions together and makes an equation.


Equilateral

An adjective describing a polygon with sides of equal length.


Evaluate

Find the value of a numerical or an algebraic expression.


Exponent

Also known as 'index' or 'power'. A number, positioned above and to the right of another, indicating repeated multiplication. 

Exponents may be fractional or negative. Examples: 81/3 = 2, which is the same as the cube root of 8.

Expression

A mathematical form expressed symbolically. Examples: 7 + 3; a2 + b2.

An expression is different from an equation in that it doesn't have an equals sign =.