The big picture
Every angle is a turn. Every turn has a number.
| Idea | Remember |
|---|---|
| Point, line, ray, segment | Told apart by their ends. |
| Two lines | They cross at one point, or they are parallel and never meet. |
| What is an angle | The turn between two rays with one vertex. |
| Measuring | A full turn is 360°. A protractor reads the size. |
| Kinds of angles | Acute < 90°. Right = 90°. Obtuse 90°–180°. Straight = 180°. Reflex 180°–360°. |
| Drawing | Centre on the vertex. Mark the degree. Draw the ray. |
| Angles around us | Compare the numbers, not the drawings. |
Open Chapter 2, Lines and Angles. You know every idea in it.