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Use the following formula to work out the area of a rectangle:

 

Rectangle area

 

We must know the base length and 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.

 

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.

Cut right-angled triangle from the left-hand side of rectangle

 

Move the right-angled triangle over to the right-hand side.

The area still hasn't changed.

 

Move right-angled triangle to right-hand side

 

Join the two pieces to form a parallelogram.

The area of this parallelogram is the same as the original rectangle.

 

Join to the piece to form a parallelogram

 

 

Area of Parallelograms

 

Parallelogram area

 

We must know the base length and 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.

 

Find the area of a parallelogram

 

Answer

To calculate the area, we must know the base length and 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

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