It's swimming time!

Geometry Level 2

A swimming pool in the shape of a circle (as shown above) is to be built in a corner of a square. Before the construction begins, the contractor must know the values of a 1 a_1 and a 2 a_2 . If you are the contractor, what is a 1 + a 2 a_1+a_2 ?

Details:

  1. 20 20 feet is the radius of the circle.

  2. Both a 1 a_1 and a 2 a_2 are perpendicular to one side of the square.

  3. Give your answer in feet.

  4. The swimming pool touches the two sides of the square.


The answer is 40.

This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try refreshing the page, (b) enabling javascript if it is disabled on your browser and, finally, (c) loading the non-javascript version of this page . We're sorry about the hassle.

1 solution

Relevant wiki: Pythagorean Theorem

The above figure is not drawn to scale. \color{#3D99F6}\text{The above figure is not drawn to scale.}

By Pythagorean Theorem

x = 2 0 2 1 0 2 = 300 x=\sqrt{20^2-10^2}=\sqrt{300}

Solving for a 2 a_2 , we have

a 2 = 20 + x = 20 + 300 a_2=20+x=20+\sqrt{300}

Solving for a 1 a_1 , we have

a 1 = 20 x = 20 300 a_1=20-x=20-\sqrt{300}

Finally,

a 1 + a 2 = 20 300 + 20 + 300 = 40 f e e t a_1+a_2=20-\sqrt{300}+20+\sqrt{300}=40~feet

Distance a 2 + a 1 = 2 × 20 = 40 a_2+a_1=2\times20=40

Note: unfortunately the software will not let me post my solution as a solution. So it's just a comment.

Marta Reece - 4 years, 1 month ago

Log in to reply

what? a 2 + a 1 = 40 ? a_2+a_1=40? proof please . .

A Former Brilliant Member - 4 years, 1 month ago

Log in to reply

You have a 2 = 2 x + a 1 a_2=2x+a_1 . So I just continued to the other side and ended up with, starting from the wall a 1 , x , x , a 1 a_1, x, x, a_1 . The first a 1 + x = 20 a_1+x=20 , as you pointed out. The second x + a 1 = 20 x+a_1=20 . Total 20 + 20 = 40 20+20=40 .

Marta Reece - 4 years, 1 month ago

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...