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Two sides of a rectangle are in the ratio 3:4. If the longer side is 20 cm, what is the perimeter of the rectangle?

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Answer:

The perimeter of the rectangle is 70 cm

Explanation:

Let us use the ratio method to solve the question

∵ Two sides of a rectangle are in the ratio 3 : 4

→ Let the width is the shorter side and the length is the longer side

∴ The ratio between the width and the length is 3 : 4

∵ The longer side is 20 cm

The length of the rectangle = 20 cm

→ By using the ratio method

→ width : length

→ 3 : 4

→ w : 20

→ By using cross multiplication

w × 4 = 3 × 20

∴ 4w = 60

→ Divide both sides by 4

∴ w = 15

The width of the rectangle = 15 cm

∵ The perimeter of the rectangle = 2(length + width)

∴ The perimeter of the rectangle = 2(20 + 15)

∴ The perimeter of the rectangle = 2(35)

∴ The perimeter of the rectangle = 70 cm

The perimeter of the rectangle is 70 cm

User Donal Lafferty
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