First find the coordinate of the center: (1,2) Then find the value pf the radio, which is the distance from the center to the perimeter: r = 4. Given center (s,t) and radius r, the formula o the equation is the following
(I think) it's 10 cms because total perimeter is 30 centimeters so there will be 5 on two sides making 10,30-10=20 and 20/2=10 which makes a total of 30 (5+5+10+10)