This sounds like someones homework. I'm risking my reputation here but here goes.
Previous Area was Pi x R x R. = Pi X 10 X 10 = 100 X Pi
Previous Perimeter is 2 X Pi X R = 2 X Pi X 10 = 20 X Pi
New shape is a rectangle with a semicircle at each end and width of 10 cm.
New Perimeter is circular bits + straight edges between them.
We know the circular bits but not how long the straight bits are so ...
Perimeter = 20 X Pi = (2 X Pi X 5) + L X 2 = 10 X Pi + (L X 2)
So L = (20 - 10) X Pi / 2 = 5 X Pi.
So the new Area is ... (Pi X 5 X 5) + (10 X 5 X Pi)
= 75 X Pi.
= 75 X 3.14 = 235.5
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