Given sheet of paper ABCD
AB = 40 cm, AD = 28 cm
⇒ CD = 40 cm, BC = 28 cm [since ABCD is rectangle]
Semicircle be represented as BMC with BC as diameter
Radius = (1/2) x BC=(1/2) x 28=14cm
Area of remaining (shaded region) = (area of rectangle) – (area of semicircle)