1. Maths Unit 8 (F) – Perimeter, Area & Volume
Finding the perimeter and area by counting
To find the perimeter of the shape to the right, you count
around the outside of the shape. The perimeter of this shape is 26cm.
To find the area of the shape to the right, you count the number of squares inside the shape. The area of this shape is 19cm².
= 1cm²
Finding the volume of a shape
Volume of Prism =
Area of the cross section x length
The cross-section is the shaded area on each of the prims below.
Formulae you need to know to find the area of different shapes
Working with circles
Finding the surface area of a 3D shape
To help you visualise the problem:
Draw the net of the shape
Label all the lengths
Use you knowledge of 2D shapes to find the area of each individual face
Add all the faces together to find the total surface area.
Key words and definitions
Perimeter – The distance around the outside of a shape
Area – Space inside a 2D shape
Volume – Space inside a 3D shape
Circumference - The distance around the outside of a circle
Diameter – A straight line passing from one side to the other of a circle through the centre
Radius – A straight line passing from the centre to the circumference of the circle
Parallelogram – A quadrilateral with two pairs of parallel lines
Trapezium – A quadrilateral with one pair of parallel lines
Prism - a solid geometric figure whose two ends are the same
Example:
Finding the surface area of the cuboid