What is a triangle?
A triangle is a 2-D polygon which has three sides.
What are the different types of triangles?
When classifying triangles by the length of their sides there are three main types: equilateral, isosceles and scalene.
Types of Triangles KS2
Angles and Triangles - Lesson 3: Special Types of Triangles
Starting off at a point where most children in Year 5 will feel comfortable, these ‘Angles and Triangles’ lessons quickly up the ante throughout the week, as children are challenged to apply their ...
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Types of Triangles KS2
Equilateral triangles
As the name suggests, the sides and angles of an equilateral triangle are all equal. This type of triangle could also be referred to as a regular triangle.
Isosceles triangles
An isosceles triangle has two equal sides and two equal angles.
Scalene triangles
A scalene triangle has no equal angles or sides.
Right-angled triangles
Some triangles can be classified by the angles within them. A common example of this is a right-angled triangle. One of a right-angled triangle's angles is 90° (a right-angle). Right-angled triangles can also be classed as scalene or isosceles triangles depending on the length of the sides.
Other examples of classifying triangles by angles include:
Acute triangles: A triangle where all the angles are less than 90°.
Obtuse angles: A triangle where one of the angles is more than 90°.
When do children learn about types of triangles?
- Year 4
- compare and classify geometric shapes, including quadrilaterals and triangles, based on their properties and sizes
- Year 6
- compare and classify geometric shapes based on their properties and sizes and find unknown angles in any triangles, quadrilaterals, and regular polygons
