Question

If the circumference of a circle is 55 cm then what is its radius and diameter

Answer 1

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$circumference \: of \: a \: circle = 2\pi \: r \\ 55 = 2 \times 3.14 \times r \\ 55 = 6.28 \times r \\ r = \frac{55}{6.28} \\ \\ r = 8.7cm \\ \\ d = 2r \\ d = 2 \times 8.7 \\ d = 17.4cm$

Answer 2

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Given :-

Circumstance of circle = 55cm

To find :-

Radius

Diameter

Solution :-

We know ,

Circumference of circle = 2πr

$\: \: 55 = 2 \times \frac{22}{7} \times r$

$\frac{55 \times 7}{2 \times 22} = r$

$\frac{5 \times 7}{2 \times 2} = r$

$\frac{35}{4} = r$

$r = 8.7~cm$

We know d = 2r

Diameter = 2 × 8.7

$~Diameter ~= ~17.4~ cm$