What is a formula?
A formula is a mathematical rule or relationship.
A formula uses letters to represent amounts that can be changed. These are called variables.
For example, the formula to work out the area of a triangle.
\(\text{area of triangle} = \frac{1}{2} b h\) (where \(b\) represents the base of the triangle and \(h\) represents the height of the triangle). \(b\) and \(h\) are variables because they can have different values, depending on the size of the triangle.
A formula shows the relationship between two or more variables. It is used to specific purpose, for example:
- working out the area of a shape or volume of an object
- converting between different units of measurement
- working out prices or costs
Question
Can you work out a formula for each of the following?
- Finding the volume of a cuboid
- Converting a length from centimetres to metres
- The cost of an item in a half price sale
- \(\text{volume of cuboid} = l \times b \times h\) where \(l\) is length, \(b\) is breadth and \(h\) is height.
- \(\text{length in metres} = \frac{\text{length in cm}}{100}\)
- \(\text{sale price} = \frac{\text{full price}}{2}\)