Question

the difference of circumfance and diameter a circle is 30 cm.calculator the diameter and area of the circle​

Answer 1

Answer:

diameter=14 cm

area=154 cm

Step-by-step explanation:

Taking pi to be 22/7,

Let the circumference be 2*22/7*r

Let, diameter be 2r [ where r is radius of the circle]

According to the problem,

=>2*22/7*r-2r=30

=>44/7*r-2r=30

=>44r-14r=210

=>30r=210

=>r=7

Hence, diameter= 2*7 cm=14 cm

Area=pi* r^2

=22/7*7*7

=154 cm

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Answer 2

Answer:

Your Question

The difference of circumfance and diameter a circle is 30 cm. Calculate the diameter and area of the circle.

Here is your Answer :-

$let \: r \: be \: the \: radius \: \: of \: the \: circle \\ circumference \: = 2\pi \: r \\ and \: area \: of \: a \: circle = \pi \: {r}^{2} \\ \\ now \: according \: to \: the \: question \\ 2\pi \: r - 2r = 30cm \\ 2r(\pi - 1)$

$let \: r \: be \: the \: radius \: \: of \: the \: circle \\ circumference \: = 2\pi \: r \\ and \: diameter \: of \: a \: circle = 2 \times r \\ \\ now \: according \: to \: the \: question \\ 2\pi \: r - 2r = 30cm \\ = > \frac{2 \times 22 \times r}{7} - 2r = 30cm \\ = > \frac{44r}{7} - 2r = 30cm \\ = > 44r - 14r = 30 \times 7 \\ = > 30r = 30 \times 7 \\ = > r = 7cm \\ therefore \: radius \: is \: equal \: to \: 7cm \\ now \: diameter \: = 2r \\ = > 2 \times 7 = 14cm \\ and \: area = \pi \: {r}^{2} \\ = > \frac{22 \times 7 \times 7}{7} \\ = > 154 {cm}^{2}$

Hope it's helpful

Answered by :-

@MissInfinite