The figure shows 2 quarter circles and a rectangle. The radius of the big quarter circle is 12 cm. The radius of the small quarter circle is 6 cm. Find the difference in the areas between the two shaded parts C and D. (Take π = 3.14 and give your answer correct to 1 decimal place.)
Area of the big quadrant
= ¹₄ x 3.14 x 12 x 12
= 113.04 cm²

Area of the small quadrant
= ¹₄ x 3.14 x 6 x 6
= 28.26 cm²

Area of the rectangle
= 12 x 6
= 72 cm²

Difference in the areas between the two shaded parts C and D
= Area of the big quadrant - (Area of the small quadrant + Area of the rectangle)
= 113.04 - (28.26 + 72)
= 113.04 - 100.26
= 12.78 
≈ 12.8 cm² (Correct to 1 decimal place)

Answer(s): 12.8 cm²