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Basic geometry terms for AQA GCSE Maths

Basic geometry terms

This page covers the following topics:

1. Points, lines and planes
2. Vertices and edges
3. Parallel and perpendicular lines
4. Types of angles
5. Polygons
6. Sides and angles of a triangle
7. Drawing diagrams

A point is a position with no size. A line can be thought of as a collection of infinitely many points that extends to infinity in both directions. It is said to have infinite length, zero height and zero width. A plane is a flat 2D-surface consisting of an infinite set of points. It is said to have infinite length and width, and zero height.

Points, lines and planes

A face is a flat surface on a 3D-shape. An edge is a line segment at the boundary where two faces meet. A vertex is a point at which line segments meet. The plural of vertex is vertices.

Vertices and edges

Parallel lines are lines that are the same distance apart for their entire length. They are denoted with a small arrow on them. Perpendicular lines are lines which cross each other at right angles. The shortest distance from a point to a line can be found by calculating the perpendicular distance between them.

Parallel and perpendicular lines

There are three types of angles: acute, obtuse and right angles. Acute angles are ones that are less than 90ยบ. Obtuse angles are ones that are more than 90ยบ, but less than 180ยบ. Right angles are ones that are 90ยบ exactly. This is indicated by a small square between the line segments.

Types of angles

Polygons are 2D-shapes with three or more sides. A polygon is said to be regular if all its sides and angles are equal. It is said to be irregular if they are not all equal.

Polygons

In a right-angled triangle, the sides are called the hypotenuse, the adjacent and the opposite. The hypotenuse is the longest side of a right-angled triangle and it is the one opposite the right angle. The opposite is the side that is directly opposite a relative angle. The adjacent is the side that is next to the relative angle.

Sides and angles of a triangle

Diagrams and shapes can be constructed from short descriptions using known properties of shapes.

Drawing diagrams

1

Define hypotenuse.

The hypotenuse is the side opposite the right angle in a right-angled triangle.

Define hypotenuse.

2

Sketch a right-angled triangle with a 30ยบ angle, a hypotenuse of 9.22 cm, an adjacent of 6 cm and an opposite of 7 cm.

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Sketch a right-angled triangle with a 30ยบ angle, a hypotenuse of 9.22 cm, an adjacent of 6 cm and an opposite of 7 cm.

3

Sketch a regular hexagon of side 8 cm, labelling its angles.

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Sketch a regular hexagon of side 8 cm, labelling its angles.

4

What is meant by an obtuse angle?

An obtuse angle is one that is more than 90ยบ, but less than 180ยบ.

What is meant by an obtuse angle?

5

State how many right angles are in a square.

There are four right angles in a square.

State how many right angles are in a square.

End of page

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