A figure is shaded as shown below :-
The horizontal boundary line and vertical boundary line of the shaded area are away from the centre of the circle with the dimension shown. Find the difference of the shaded area and unshaded area.
Answer :
For a primary school maths problem, it seems to be impossible to calculate the difference as complex formula for such calculation is not covered in primary school. Moreover, the radius or the diameter of the circle was not given. However, if you use some visual analysis, you will simplify the area of the shaded part as below :-
For a primary school maths problem, it
seems to be impossible to calculate the difference as complex formula
for such calculation is not covered in primary school. Moreover, the
radius or the diameter of the circle was not given. However, if you
use some visual analysis, you will simplify the area of the shaded
part as below :-
By dropping 2 mirror image vertical
line and horizontal line and flip the 2 portion, the shaded portion
will cover the semi-circle plus 2 rectangles with the dimension
shown.
The unshaded area will cover the
semi-circle minus the 2 rectangles. So the difference will be 4
rectangles
Difference of the shaded area and
unshaded area = 4 x 4cm x 6cm
= 96 cm2
