A rectangular piece of paper with length 25 cm and width 10 cm has two semicircles cut out of it. Find the area of the paper that remains. Use the value 3.14 for π, and do not round your answer

Answer 1

Two semicircles, if they are the same size, make up one whole circle.

The paper has an area of 25*10 = 250 cm²

A circle has an area of pi*r² , or 3.14*r²

A semicircle has an area of exactly half of that, or 3.14*r² / 2 = 1.57*r²

The area of the paper that remains is calculated by taking the area of the whole paper (250 cm²) and subtracting the area of the circle, or two semicircles if they are different sizes.

We can write that as:

A = 250 - 3.14*r² - if the semicircles are the same size

or

A = 250 - 1.57*r₁² - 1.57*r₂² - if the semicircles are have different radii (r₁ and r₂)

We cannot solve any further without knowing the radius of the semicircles.