In GCSE Maths, 'alternate angles' are a pair of angles that occur on opposite sides of a straight line that intersects two parallel lines. These angles are equal in measure.
When you have two parallel lines and a line that intersects them, alternate angles are found in a "Z" shape, with one angle inside the Z and the other outside.
Recognising alternate angles can help with problem solving in polygons and "show that" questions within geometry.
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