Answer:
Exact area = 272 - 28.125pi square cm
Approximate area = 183.6875 square cm (when using pi = 3.14)
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Step-by-step explanation:
The trapezium has the parallel sides of 12+13 = 25 cm and 15 cm. Those vertical sides average to (25+15)/2 = 40/2 = 20. Multiply this with the height of the trapezium to get 20*24 = 480 sq cm as the area.
You could also use this trapezium area formula
A = h*(b1+b2)/2
A = 24*(25+15)/2
A = 480
Whichever method you use, the trapezium has an area of exactly 480 square cm.
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The paralellogram has base of 13 and height of 16, so its area is base*height = 13*16 = 208 sq cm
The semicircle has area of 0.5*pi*r^2 = 0.5*pi*7.5^2 = 28.125pi square cm. Notice that I used r = 7.5 which is half of the diameter 15 cm.
The parallelogram and semicircle areas add to 208+28.125pi
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Subtract this from the area of the trapezium to wrap things up
480 - (208+28.125pi)
480 - 208 - 28.125pi
272 - 28.125pi
This is the exact area of the blue shaded region in terms of pi
To get the approximate area, replace pi with something like 3.14 and compute.
So 272 - 28.125pi = 272 - 28.125(3.14) = 183.6875 is the approximate area when pi = 3.14
Use more decimal digits of pi to get a more accurate value.