Circled Square

Geometry Level 1

The circumcircle of a square has an area of π \pi . What is the area of the square?


The answer is 2.

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5 solutions

Xiangchen Kong
Jan 28, 2016

Since the area of the circumcircle is π,we can get the radius of the circle by using the formula:πr^2=π r^2=1 Apparently r=1 Since it's a square ,each side of it has the ratio √2:1 to half of the diagonal(45˚) Therefore , the area of the square would be √2 *√2 =2. Fairly straightforward. A classic square /circumcircle question.

Achille 'Gilles'
Feb 2, 2016

Fin Moorhouse
Jan 28, 2016

π r 2 = π \pi r^2 = \pi , so r 2 = 1 r^2=1 , and so r = 1 r=1 . If r = 1 r=1 , consider a right-angled triangle with hypotenuse of length x x (the side length of the square) and the other two sides of length 1 (the grey lines in the square). x 2 = 2 x^2=2 , so x = 2 x=\sqrt{2} . The area of the square is 2 2 = 2 \sqrt{2}^2=\color{#20A900}{\boxed{2}} .

Yasir Soltani
Feb 2, 2016

As the area of the circumcircle is π \pi A = π r 2 r = 1 \because A=\pi r^2 \Rightarrow r=1 thus the total area of the square is the sum of two triangles of base 2 2 and height 1 1 A s = 2 × 1 2 × 1 × 2 \therefore A_s=2\times \frac{1}{2}\times 1 \times 2 A s = 2 A_s=2 .

Youssef Hassan F
Feb 3, 2016

bec the rule of the area of the circle = r ^2 * 3.1415......... and the area of this circle = 3.1415....... so r ^ 2 must be 1 so r = 1 so the diameter = 2 and as you see above the diameter is the diagonal of the square and the hypotenuse of 2 right angled triangles with 45 degrees on both two other sides so by Pythagorean theorem 2^2 = 4/2=2 so the side of the triangle is sqrt(2) so the side length of the square is sqrt(2) so the area of the square is sqrt(2) ^ 2 means 2

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