Maths Dictionary · JSS 1, JSS 2
Protractor
Simple meaning
A semicircular tool for measuring and drawing angles.
Example
Put its centre on the vertex and read from the 0° line.
See it
From the Angles and Their Types lesson. Try moving things around.
60° + 48° + 72° = 180°
This is an acute-angled, scalene triangle. Drag any corner!
Put the three angles together and they make a straight line: 180°.
Your task: make a right-angled triangle
Drag a corner until one angle shows 90°. Tip: line two sides up with the grid lines.