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BECE Mathematics 2013 Paper

Question : 20

Total: 40

154 \mathrm{cm}^2

\pi = \; \frac{22}{7}

Solution:

Area of a circle

= \pi r^2

Where

r =

radius

Diameter

= 2 x

radius

154 = \; \frac{22}{7} \times r^2

Get rid of the fraction by multiplying both sides of the equation by the denominator (7)

154 \times 7 = 22 \times r^2

Divide both sides of the equation by 22

\; \frac{154 \times 7}{22} = r^2

Note: 22 divides itself once and 154, 7 times.

\; 7 \times 7 = r^2

\; 7^2 = r^2

Since the powers are the same, the bases are also the same.

7 = r

Radius

= 7 \mathrm{cm}

Diameter

= 2 x

radius

Diameter

= 2 \times 7 \mathrm{cm} = 14 \mathrm{cm}

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