Angles & Lines
Maths: Edexcel IGCSE Higher, topic 4.1.1
Types of Angle
There are 4 important types of angle:
Right angle
- A right angle is an angle of 90° and is indicated by a square angle marker.
Acute angle
- An acute angle is one that is less than 90°.
Obtuse angle
- An obtuse angle is one that is greater than 90° but smaller than 180°.
Reflex angle
- A reflex angle is greater than 180° but smaller than 360°.
Geometry Basics
Vertices and edges
- The corners of a polygon are called vertices and the sides are called edges.
Plane
- A plane is a flat 2 dimensional surface like the surface of a table.
Parallel lines
- If two lines are parallel they point in exactly the same direction and will never meet.
- Parallel lines are indicated by drawing matching arrows on the lines.
- If there are two different pairs of parallel lines then different arrows are used for each pair.
Perpendicular lines
- Two lines are perpendicular if the angle between them is a right angle.
Test yourself on Angles & Lines
What type of angle is this?
What type of angle is this?
What type of angle is this?
What type of angle is this?
What do we call an angle smaller than 90°?