Equilateral triangles have three equal-sized angles and three edges of equal length. They are regular triangles.

Scalene triangles have three different-sized angles and three different-sized edges (sides).

Isosceles triangles have two equal-sized angles and two sides of the same length.

A right-angled triangle has exactly one 90° interior angle.

Formalising understanding of triangles from KS2

Maths

This unit gives pupils the opportunity to explore polygons and begin to generalise their understanding of interior/exterior angles in regular polygons. In the future unit, pupils will use the geometrical properties of a rhombus to perform various constructions

In this unit, pupils learnt how to calculate with angles at a point and angles on a straight line. In this unit, pupils extend their knowledge about angles in lines

In this unit pupils will investigate internal and external angles of polygons and angles made with a transveral and parallel lines. Pupils will develop their ability to formally prove properties of polygons to generalise.

Geometrical properties: polygons

Which of these statements are true about this triangle?

This triangle is scalene. Which of these are possible values of $$b$$?

It is impossible to know the size of angle $$c$$.

Which of these statements are correct for this triangle?

It is impossible to know any angles in this triangle, as none are given.

A different side of this triangle has a length of 40 cm.

A different side of this triangle has a length of 60 cm.

An equilateral triangle has one side of length 40 cm. Which of these statements are correct?

An isosceles triangle has an angle of 90°, and a side of length 19 cm. What is the size of one of its other angles, in degrees? {{}}°.

impossible to have this triangle with an angle of 30°

Three different triangles each have an angle of 30°. Match the name of each triangle to their possible angles.

These three angles lie around a point on a full turn. $$b$$° = {{}}°.

Angle $$c$$° and 42° are vertically opposite.

Angle $$c$$° and 42° are supplementary.

This diagram shows four angles around two line segments that meet at an intersection. Which of these statements are correct for angle $$c$$°?

Angle $$d$$° and 42° are vertically opposite.

Angle $$d$$° and 42° are supplementary.

This diagram shows four angles around two line segments that meet at an intersection. Which of these statements are correct for angle $$d$$?

PQ and RS are straight line segments. $$e$$° = {{}}°.

PQ and RS are straight line segments. Match each angle to its size.

Starter Quiz