Geometry, Angles, and Shapes

Geometry is an important part of the SET 11+ maths papers. You will need to know the properties of 2D and 3D shapes, calculate angles, understand symmetry, and work with coordinates. On Stage 2, you must show your angle calculations step by step. This lesson covers all the geometry you need.

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Types of Angles

Angle type	Size	Example
Acute	Less than 90°	35°, 72°
Right angle	Exactly 90°	Corner of a square
Obtuse	Between 90° and 180°	120°, 155°
Reflex	Between 180° and 360°	210°, 300°

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Key Angle Rules

These rules come up again and again on the SET:

Rule	Fact
Angles on a straight line	Add up to 180°
Angles at a point	Add up to 360°
Angles in a triangle	Add up to 180°
Angles in a quadrilateral	Add up to 360°
Vertically opposite angles	Are equal

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Worked Example 1: Angles on a Straight Line