Use the following formula to work out the area of a rectangle:
We must know:
- the base length
- the perpendicular height from the base to the top.
Area of rectangle = base × height
Now, try this with a piece of paper.
Start with a rectangle.
Cut off a right-angled triangle from the left-hand side and separate the two pieces.
The area of the two pieces together will be the same as the original rectangle.
Move the right-angled triangle over to the right-hand side.
The area still hasn't changed.
Join the two pieces to form a parallelogram.
The area of this parallelogram is the same as the original rectangle.
Area of Parallelograms
We must know:
- the base length
- the perpendicular height from the base to the top. (NOT the slant height)
Area of parallelogram = base × height
Example
Calculate the area of this parallelogram in cm2.
Answer
To calculate th area, we must know:
- the base length
- the perpendicular height from the base to the top. (NOT the slant height)
The base length is 10 cm.
The slant height is 7 cm, which we do not need.
The perpendicular height is 6 cm.
Area = Base × Height = 10 × 6 = 60 cm2