In the previous topic, by counting, we obtained an area of 15cm^{2} for a 5cm by 3cm rectangle.

Notice also that 5 × 3 = 15

Thus, the area of a rectangle = “length or width” × “height”

Area = w × h

Where w is the width

Where h is the height

If Area is given then to find h or w, we use the following formula:

Area = w × h

width, w = \( \frac{Area}{h} \)

height, h = \( \frac{Area}{w} \)

### Example 1:

Calculate the area of a rectangle of length 50cm and 30cm in width.

**Solution:**

Area = width × height

= 30cm × 50cm

= 150cm^{2}

### Example 2:

The area of a rectangle carpet is 20m^{2}. Find the length of the shorter side in metres if the length of the longer side is 4000mm.

**Solution:**

First, we have to convert 4000mm to m (millimetres to metres)

1000mm = 1m

So 4000mm = \( \frac{1}{1000} \: \times \: \scriptsize 4000 \\ = \frac{4000}{1000} \\ = \scriptsize 4m\)

If A = w × h

height h = \( \frac{Area}{w} \\ = \frac{20m^2}{4m} \\ = \scriptsize 5m \)

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