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This problem attracted several correct answers anonymously submitted by students at Madras College . This solution is included because of its brevity:
$AD = 1$ unit, which is the radius of the circle centre
$A$.
The coordinates of $P$ are $(AD \cos 60^{\circ} , AD \sin
60^{\circ} ) = ({1\over2}, {\sqrt{3}\over2})$
Similarly coordinates of $Q$ are $(AD \cos 30^{\circ} , AD
\sin 30^{\circ} ) = ( {\sqrt{3}\over2},{1\over2})$ and angle $PAQ$
is $30^{\circ}$.
Area of square $PQRS = ({1\over2} - {\sqrt{3}\over2})^2 +
({\sqrt{3}\over2} - {1\over2})^2 = 2 - \sqrt{3}$
Area of a segment $PQ$ = [${1\over12}$ area of circle, centre
$A$ radius $1$ unit] - [Area of Triangle $APQ$ ]
Using the formula ${1\over12}\pi r^2$ for the $30$ degree
sector and ${1\over2} ab\sin C$ for the area of the triangle we
get:
Area of a segment $PQ = {1\over12} \pi.1.1 -
{1\over2}.1.1.{1\over2} = {\pi\over12} - {1\over4}$ \par Bounded
area = area of square $PQRS$ + area of 4 equal segments
Bounded area $= 2 - \sqrt{3} + 4 ({\pi\over12} - {1\over4}) =
1 + {\pi\over3} - \sqrt{3}$
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Find the perimeter and area of a holly leaf that will not lie flat (it has negative curvature with 'circles' having circumference greater than 2πr).
Given a square ABCD of sides 10 cm, and using the corners as centres, construct four quadrants with radius 10 cm each inside the square. The four arcs intersect at P, Q, R and S. Find the area enclosed by PQRS.
A white cross is placed symmetrically in a red disc with the central square of side length sqrt 2 and the arms of the cross of length 1 unit. What is the area of the disc still showing?