A pair of angles at different vertices on the same side of a transversal in equivalent positions.

A pair of angles both between or both outside two line segments that are on opposite sides of the transversal that cuts them.

Co-interior angles are on the same side of the transversal line and in between the two other lines.

An interior angle is an angle formed inside a polygon by two of its edges.

An exterior angle is an angle on the outside of a polygon between an extension of an edge and its adjacent edge.

Missing angles

Maths

Checking understanding of angles from KS2

Securing understanding of angles from KS2

Formalising understanding of triangles from KS2

Formal angle notation

Corresponding angles

Alternate angles

Co-interior angles

Angles on parallel lines traversed by a straight line

The sum of the interior angles of any triangle

Using the sum of the interior angles of a triangle

Interior angles of a polygon

Deriving the sum of interior angles in multiple ways

Exterior angles of polygons

Interior and exterior angles of regular polygons

Problem solving with polygons

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

Adjacent angles on a straight line sum to 180°.

Co-interior in parallel lines angles sum to sum to 180°.

∠ABG = 112°. Based on this information, which justification could be used to explain why ∠CBG = 68°?

Alternate angles in parallel lines are equal.

Corresponding angles in parallel lines are equal.

Which justification could be used to explain why ∠CGF = ∠GCD?

alternate angles in parallel lines are equal

corresponding angles in parallel lines are equal

adjacent angles on a straight line sum to 180°

co-interior angles in parallel lines sum to sum to 180°

Match each statement with its justification.

Given ∠EGC = 82°, then ∠CGB = {{}}°.

The pentagon in the image is regular. The size of the shaded angle is {{}}°.

The image shows a regular pentagon and a regular hexagon. The size of the shaded angle is {{}}°.

In which cases are the angles always equal to each other?

Co-interior angles on parallel lines sum to {{}}°.

Match each shape with the sum of its interior angles.

they are alternate angles on the parallel lines

they are corresponding angles on the parallel lines

Starter Quiz

In which cases are the angles always equal to each other?