# Finding the Area (parameter)

• July 31st 2013, 07:04 AM
Telo
Finding the Area (parameter)
Given is a square, ABCD, the lenght of a side is equal to "a". A and D are centers of circles, BD and AC are arcs of circles and they intersect each other in K. Find the area of brightened figure on the picture

Attachment 28933
• July 31st 2013, 07:56 AM
Soroban
Re: Finding the Area (parameter)
Hello, Telo!

Quote:

Given square ABCD with side $a.$
A and D are centers of quarter-circles.
The arcs intersect at K.
Find the area of shaded region.

Code:

    B *-*-------*-* C       |    K*:::::|       |  */..*:::|       | *./.....*:|       |*./.......*| a       |./.........|       */..........*     A *-----------* D             a

Draw chord $AK.$

The area of quarter-circle $AKCD$ is:- $\tfrac{1}{4}\pi a^2$

The area of sector $AKD$ is:- $\tfrac{1}{6}\pi a^2$

The area of segment $AK$ is:- $\tfrac{1}{6}\pi a^2 - \tfrac{\sqrt{3}}{4}a^2$

$\text{Shaded region} \:=\:\text{(quarter-circle)} - \text{(sector + segment)}$

. . . . . . . . . . $=\;\tfrac{1}{4}\pi a^2 - \left(\tfrac{1}{6}\pi a^2 + \left[\tfrac{1}{6}\pi a^2 - \tfrac{\sqrt{3}}{4}a^2\right]\right)$

. . . . . . . . . . $=\;\left(\tfrac{\sqrt{3}}{4} - \tfrac{\pi}{12}\right)a^2$
• July 31st 2013, 08:00 PM
ibdutt
Re: Finding the Area (parameter)
Quote:

Originally Posted by Telo
Given is a square, ABCD, the lenght of a side is equal to "a". A and D are centers of circles, BD and AC are arcs of circles and they intersect each other in K. Find the area of brightened figure on the picture