Lesson 13 of 15
The big picture
Show on a big screenEvery tile in the corridor now has a name.
| Idea | How it goes |
|---|---|
| Four sides | Straight, closed, no side crossing another. |
| Corner total | Cut along a diagonal inside the shape. Four angles total 360°. |
| Diagonals | A line to a non-neighbour corner. A quadrilateral has 2. |
| Five names | Trapezium, parallelogram, rectangle, rhombus, square — each a list. |
| Parallelogram | Sides match, angles match, next-door angles total 180°. |
| Halving | A parallelogram's diagonals cut each other in half. |
| Matching lengths | Equal diagonals plus a parallelogram means a rectangle. |
| Square crossing | Four equal sides make the diagonals cross at 90°. |
| Several names | A square is also a rhombus, a rectangle, a parallelogram. |
| Building one | Four sides need a fifth measurement to fix one shape. |
Part I, Chapter 4 of your textbook is Quadrilaterals. Read it next.