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Area of a circle is in direct variation with the square of the radius of the circle. If the area of a circle is 616 sq.cm., then the radius is 14 cm. Find the area of the circle whose radius is 42 cm.
Options
Option A is correct
5544 sq.cm.
Option B
3850 sq.cm.
Option C
2464 sq.cm.
Option D
4455 sq.cm.
Explanation
The area of a circle is in direct variation with the square of its radius , which means , where is the constant of proportionality (in this case, ). Given: sq.cm. when cm. We can find the constant (which is ): . So, . Now, we need to find the area when cm. sq.cm. Alternatively, since , we have . We notice that . So, . sq.cm. Therefore, the area of the circle whose radius is cm is sq.cm.