Angle facts

Work out missing angles with reasons.

Roads crossing

Where two roads cross, four angles are made. We can work out unknown angles using angle facts. Each answer needs a reason.

Angles on a line and at a point

Angles on a line add to 180°. Angles at a point add to 360°. Missing angle = 180° − known angle.

Vertically opposite angles

Two crossing lines make 4 angles. Vertically opposite angles are equal. Neighbouring angles add to 180°.

Triangles and quadrilaterals

The angles of a triangle add to 180°. In a triangle with 50° and 60°, the third is 70°. The angles of a quadrilateral add to 360°.

Drawing angles

Draw a straight line. Put the protractor’s centre on one end. Count from 0 to 65 and make a mark. Join it to the end of the line. An angle is a measure of turn: 65° is a little less than three quarters of a right angle.

What I learnt

I can find missing angles on a line and at a point.
I know vertically opposite angles are equal.
I can use angle sums of triangles and quadrilaterals.