Curved length of the semicircle
= 1/2 x pi x diameter
= 1/2 x pi x (15 x 2)
= 47.1238898 m
~ 47.12 m

Perimeter of semicircle
= 47.12... + 15 + 15
= 77.12...
~ 77.12 m

To find the perimeter, you need to know what kind of lengths are surrounding the entire shape. Are they straight lines? Are they curves?

From here, you will then identify what lengths to find.

For a circle, the curved surrounding has a length equal to pi x diameter. Diameter is basically a long length from one end of the circle to the other circle, and radius is the length from one end of the circle to the centre of the circle.

For a semicircle, the curved length is half of this (obviously, since we cut the circle into two equal parts).

For the quarter circle.

Curved length
= 1/4 x pi x diameter
= 1/4 x pi x (17 x 2)
= 26.70353756
~ 26.70 cm

Total perimeter
= 26.70... + 17 + 17
= 60.70...
~ 60.70 cm

Thank you!