# Internal angles in a quadrilateral

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## Lesson details

### Key learning points

- In this lesson, we will be able to use triangles to deduce the sum of the interior angles in a quadrilateral. We will also be able to find unknown angles in quadrilaterals.

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This content is made available by Oak National Academy Limited and its partners and licensed under Oak’s terms & conditions (Collection 1), except where otherwise stated.

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### 6 Questions

Q1.

Decide if the following statement is always, sometimes or never true: The diagonals of a quadrilateral intersect.

Always true

Never true

Q2.

Decide if the following statement is always, sometimes or never true: The diagonals of a rhombus are perpendicular.

Never

Sometimes

Q3.

Decide if the following statement is always, sometimes or never true: The diagonals of a trapezium are perpendicular.

Always

Never

Q4.

Decide if the following statement is always, sometimes or never true: The diagonals of a quadrilateral are the same length

Always

Never

Q5.

Which line (A, B or C) is a diagonal of this shape?

A

B

They are all diagonals of the rectangle

Q6.

The diagonals of a three quadrilaterals are shown, draw and name the shapes.

Isosceles trapezium, Kite, Rhombus

Parallelogram, Kite, Delta

Rhombus, Rectangle, Delta

### 6 Questions

Q1.

Find the size of the missing angle.

155 degrees

260 degrees

Q2.

Calculate the missing angle, labelled x

180 degrees

90 degrees

Q3.

Find the missing angles, x, y and z

x = 38, y = 142, z = 38

x = 38, y = 52, z = 142

Q4.

Find the size of the missing angles.

x = 123, y = 100

x = 68.5, y = 68.5

Q5.

Shown below is a rhombus. Calculate each of the missing angles

They are all diagonals of the rectangle

x = 11.5, y = 141.5, z = 141.5

x = 23, y = 314, z = 314

Q6.

Find the size of the missing angle.

180 degrees

74 degrees