Fantastic effort! You have decided to spend some valuable time practising for your Maths SATs test.

In this activity, we will look at how to find the **missing angle** in a shape or around a point.

How do we find missing angles on a straight line?

The angles on a straight line add up to **180°.**

To calculate the missing angle on a straight line, take away the known angle from **180°.**

**180° - 65° = 115°**

How do we find missing angles in a full turn?

The angles in a full turn up add up to **360°.**

To calculate the missing angle in a full turn, take away the known angle from 360°.

**105° + 90° + 25° = 220°**

**360° - 220° = 140°**

How do we find missing angles on intersecting lines?

All 4 angles will add up to **360°.**

Opposite angles on a cross are equal.

**Step 1** (we know the angle opposite 65° is also worth 65° so add these together): **65° + 65° =130°**

**Step 2** (subtract the total of these 2 angles from 360°): **360° - 130° = 230°.**

**Step 3** (Divide this total by 2 to find what each of the 2 remaining angles is worth): **230°÷ 2 =115°**

How do we find missing angles in a triangle?

The angles in a triangle always add up to **180°.**

To find the missing angle, add together the known angles and subtract from 180°.

If you are given a triangle like this, but asked to find the missing angle, focus only on the angles given, ignore the other information.

**57° + 90° = 147°**

**180° - 147° = 33°**

How do we find missing angles in a quadrilateral?

A quadrilateral is a shape with 4 straight sides, like a square, rhombus, parallelogram, trapezium, rectangle.

The angles in a quadrilateral will add always add up to **360°**

To find the missing angle, add together the known angles and then subtract from 360**°**

**90° + 90° + 40° = 220°**

**360° - 220° = 140**

Now we have revised those key facts, time to have a go at some practice questions!