11)  

if you can see, the unshaded region is a semi ellipse

lets compute for the 1st and 2nd radius of the ellipse

a = 12/2 = 6 m

b = 6/2 = 3 m

area of semi ellipse = (abπ)/2 = (6*3*π)/2 = 9π m²

but there are 2 semi ellipse

therefore

2(9π m²) = 18π m² = 56.55 m²

area of the rectangle = 12*6 = 72 m²

area of the shaded region = 72 - 56.55  

= 15.45 m²

12)

radius if the large semi circle = 2 + 2 = 4 cm

area of the large semi circle = 4²*π/2 = 25.13 cm²

area of the small semi circle = 2²*π/2 = 6.28 cm²

but there are two small semi circle

2(6.28) = 21.56 cm²

area of the shaded region = 25.13 - 21.56 = 3.57 cm²

13)

assume the unshaded region is a square

therefore: height of the triangle is 12 cm

area of the square = 12² = 144 cm²

area of the trapezoid = (12 + 20)*12/2 = 192 cm²

area of the shaded region = 192 - 144 = 48cm²

14)

area of the large circle = π*14² = 615.75 cm²

area of the small circle = π*7² = 153.94 cm²

area of the shaded region = 615.75 - 153.94 = 461.81 cm²

Answer:

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