Remark
I take it that every bit of the blue line (including the diameter is used in making the semicircle and it's diameter
Formula
d + pi*d/2 = "Perimeter" = P
pi = 22/7
P = 144
Solve
d + pi*d/2 = P
d + (22/7)/2 * d = P
d(1 + 22/7//2 ) = 144
d(1 + 22/14) = 144
[tex]\dfrac{d*(14+22)}{14}[/tex] Multiply by 14
d*36 = 14 * 144
d*36 = 2016 Divide by 36
d = 56
Check
56 + 56* (22/7)/ 2 =? 144
56 + 8*22/2 =? 144
56 + 88 = ? 144
144 = 144 it checks.
