Perimeter is the size of the length that surrounds a shape. There are a bunch of perimeter formulae for some common shapes that you need to be familiar with:
- Perimeter of circle: 2πr
- Perimeter of semi-circle: πr
- Perimeter of square: 4a (where a is length of each side)
- Perimeter of rectangle: 2 × (length + width)
- Perimeter of triangle: sum of the three sides.
Calculate the perimeters of the following shapes.