Opposite - GCSE Maths Definition

The word 'opposite' can have a few different meanings in GCSE Mathematics.

In reference to geometry/shapes, we could talk about 'opposite sides' or 'the side opposite an angle'. For example, the two parallel sides of a trapezium are opposite each other. The side of a right-angled triangle opposite the right-angle is always the hypotenuse. Also in geometry, 'vertically opposite angles' are often just called 'opposite angles' (but we'd recommend always using the phrase vertically opposite in your exam!).

In algebraic work, opposite may refer to opposite operations, technically called inverse operations (or inverse functions). For example, the opposite of the function "add 6, then multiply by 2" would be "divide by 2, then subtract 6". Also in equations, opposite may refer to the sides of equations, particular when solving them; for example, the first stage of solving the equation would usually be described as "subtracting 3 from both sides", but it could also be said as "take the 3 to the opposite side (and change its sign)."

When drawing reflections on a coordinate grid, we may refer to a reflection as "drawing the image on the opposite side of the mirror line". Opposite generally means what you would expect it to, but it is important to be aware of its various uses in GCSE Mathematics.