# Math Help - Rectangles and circles

1. ## Rectangles and circles

Hi guys. I may be being really dumb but I just wanted to check this. If a rectangle is laid flat and a circle slowly moves towards it until it is just touching the rectangle, what shape would you draw if you put a pencil in the centre of the circle and drew around the rest of the rectangle?

Apologies if I'm being really dumb but just wanted to check.

http://www.mathhelpforum.com/math-he...-0140-rofl.gif

2. Hello, Carlos!

If a rectangle is laid flat and a circle is just touching the rectangle, what shape would you draw
if you put a pencil in the centre of the circle and drew around the rest of the rectangle?

If I understand the problem, we are rolling a circle around a rectangle
. . and tracing the path of its center.

The figure would be a "rectangle" with rounded corners.

The shaded region is the given rectangle.
$R$ is the radius of the circle.

Code:
              *   *   *   *   *
*   :               :   *
*     :R              :     *
*      :               :      *
:               :
* - - - o---------------o - - - *
*   R   |:::::::::::::::|       *
*       |:::::::::::::::|       *
*       |:::::::::::::::|       *
*       |:::::::::::::::|       *
*       |:::::::::::::::|       *
*       |:::::::::::::::|       *
* - - - o---------------o - - - *
:               :   R
*      :               :      *
*     :              R:     *
*   :               :   *
*   *   *   *   *

3. Hello Soroban,

Thank you very, very much for that. You've put a worried mind at ease. Kind of you to take the time to reply!

Warm regards

Carlos