Two Circles

Geometry Level 1

$\Gamma_1$ is a circle with area $27$ . $\Gamma_2$ is a circle whose radius is 3 times the radius of $\Gamma_1$ . What is the area of $\Gamma_2$ ?

The answer is 243.

1 solution

Arron Kau Staff
May 13, 2014

Since $\Gamma_2$ has a radius which is 3 times that of $\Gamma_1$ , hence they are similar with a ratio of $3$ . As such, the area of $\Gamma_2$ will be $3^2 = 9$ times the area of $\Gamma_1$ , which is equal to $9 \times 27 = 243$ .

Two Circles

The answer is 243.

1 solution

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