The hardest part is finding the length of the curve at the top. To find arc length, multiply the circumference by the arc angle divided by full angle (360°) in a circle. Or:
x, the arc angle in a semicircle, is 180°.
r, the radius is 7/2 = 3.5.
Now just plug the numbers in and solve for arc length, s.
s = 2π(3.5)(1/2) ≈ 11.00
Now just add up all the sides. 11cm + 10cm + 10cm + 7cm = 38 cm.