Angles & Angle Facts

Create and classify angles, then apply the essential totals for lines, points and polygons.

Curriculum rangeYears 4–9

Drag the pink arm (or tap a preset) to change the angle and see what it's called.

60°

Acute angle

Learning notes

Angles & Angle Facts essentials

Keep these rules beside you while you explore and practise.

1Classify angles

Acute angles are below $90^\circ$ , right angles are $90^\circ$ , obtuse angles lie between $90^\circ$ and $180^\circ$ , and reflex angles lie between $180^\circ$ and $360^\circ$ .

2Core totals

\text{Line}=180^\circ\quad\text{Point}=360^\circ

\text{Triangle}=180^\circ\quad\text{Quadrilateral}=360^\circ

3Vertically opposite angles

When two straight lines cross, vertically opposite angles are equal.

4Show the equation

Translate the diagram into an angle equation, solve it, then check the result is sensible for the angle type shown.

💡Do not judge by appearance: diagrams may not be drawn accurately; use the marked facts.