Question

49) The circumference of a circle is twice the perimeter of a rectangle. The area of the circle
is 3850sq cm. What is the area of the rectangle if the length of the rectangle is 30cm ?
A)750sq cm
B)620sq cm
C)700sq cm D)650sq cm
E)None​

Answer 1

Answer:

Option A is correct..............

Answer 2

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Solution:-

$area \: of \: circle \: = \: \frac{22}{7} \times {r}^{2}$

$= > 3850 = \frac{22}{7} \times {r}^{2}$

$= > {r}^{2} = 3850 \times \frac{7}{22}$

$= > {r}^{2} = 175 \times 7$

$= > {r}^{2} = 1225$

$= > r = \sqrt{1225}$

$= > \: r = 35$

Then

$circumference \: of \: circle \: = 2 \pi \times r$

$= > 2 \times \frac{22}{7} \times 35$

$= > 10 \times 22$

$circumference \: of \: circle = > 220$

perimeter of Circle = 2 (30 + b )

$= > \frac{220}{2} = 60 + 2b$

$= > 110 - 60 = 2b$

$= > 5 0 = 2b$

$= > b = 25$

$area \: of \: rectange = \: 25 \times 30$

$= 750 \: sq.cm$

Hence , your option A is correct