Explanation:
normally the perimeter of a rectangle is
2×length + 2×width
in this case here one of the sides in that calculation has to be replaced by the outer circumference of the semicircle.
but which one ? you did not say, whether the semicircle is attached to a length or to a width of the rectangle.
the circumference of a circle is
2×pi×r
r being the radius (= half of the diameter).
so, the outer circumference of a semicircle is
2×pi×r/2 = pi×r
since we don't know the side of the rectangle, I am giving you both calculations here, and you have to pick the right one that fits your original problem definition.
if it is attached to a length (25 ft), then the radius of the semicircle is
25/2 = 12.5 ft
and the whole perimeter is
length + semicircle + 2×width =
= 25 + pi×12.5 + 2×29 =
= 25 + 39.26990817... + 58 = 122.2699082... ft
if it is attached to a width (29 ft), then the radius of the semicircle is
29/2 = 14.5 ft
and the whole perimeter is
2×length + semicircle + width =
= 2×25 + pi×14.5 + 29 =
= 50 + 45.55309348... + 29 = 124.5530935... ft