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4.5 K) Area of Parallelograms – Part 1
4.5 K) Area of Parallelograms – Part 1
A parallelogram is a quadrilateral that has opposite sides that are parallel to each other; there are two pairs of parallel sides.
We are able to work out the area of a parallelogram by multiplying the base by the perpendicular height (the perpendicular height is the distance from the base to the opposite side).
With this formula, we need to make sure that we are using the perpendicular height of the parallelogram rather than the length of the sloping side. Sometimes in the exam you will be given certain values for the parallelogram and asked to work out the area. In order to work out the area, we must first find the perpendicular height and then use the above formula. We will see a few examples where this is the case in the next section.
Example 1
What is the area of the parallelogram below?
What is the area of the parallelogram below?
We are given the value of the base and the perpendicular height. This means that we can find the area by subbing the values into the area of a parallelogram formula.
The area of this parallelogram is 24 cm2.
Example 2
The area of the parallelogram below is 56 cm2. What is the length of the base?
We are given the area of this parallelogram and we have the perpendicular height (7 cm). We are asked to work out what the length of the base is and we can do this by subbing the values that we currently have into the area of a parallelogram formula. We can then solve to find the length of the base (the value of b).
We want to find the value of b and not 7b. Therefore, we need to divide both sides of the equation by 7.
The base of the parallelogram is 8 cm.