+118723 What about the curved bit anon?
find the perimeter of semi circular plate of radius 3.85cm
$$\\P=0.5* 2\pi r\;\; +\;\; 2r$$
$${\mathtt{0.5}}{\mathtt{\,\times\,}}{\mathtt{2}}{\mathtt{\,\times\,}}{\mathtt{\pi}}{\mathtt{\,\times\,}}{\mathtt{3.85}}{\mathtt{\,\small\textbf+\,}}{\mathtt{2}}{\mathtt{\,\times\,}}{\mathtt{3.85}} = {\mathtt{19.795\: \!131\: \!716\: \!320\: \!704}}$$
P = 19.8 cm
perimeter of semi circular plate =2r (r=radius)=2*3.85=7.7cm
the diameter doesn't change no matter the circular plate is half or not!
+118723 What about the curved bit anon?
find the perimeter of semi circular plate of radius 3.85cm
$$\\P=0.5* 2\pi r\;\; +\;\; 2r$$
$${\mathtt{0.5}}{\mathtt{\,\times\,}}{\mathtt{2}}{\mathtt{\,\times\,}}{\mathtt{\pi}}{\mathtt{\,\times\,}}{\mathtt{3.85}}{\mathtt{\,\small\textbf+\,}}{\mathtt{2}}{\mathtt{\,\times\,}}{\mathtt{3.85}} = {\mathtt{19.795\: \!131\: \!716\: \!320\: \!704}}$$
P = 19.8 cm
