Question 881850
{{{drawing(300,300,-2,10,-2,10,grid(1),
circle(1,3,0.2),
circle(7,3,0.2),
circle(7,7,0.2),
circle(4,7,0.2),
line(1,3,7,3),
line(7,3,7,7),
line(7,7,4,7),
line(4,7,1,3))}}}
From (1,3) to (7,3) is 6 units.
From (7,3) to (7,7) is 4 units.
From (7,7) to (4,7) is 3 units.
You need to calculate the distance from (4,7) to (1,3).
Use the distance formula,
{{{D^2=(x[1]-x[2])^2+(y[1]-y[2])^2}}}
{{{D^2=(4-1)^2+(7-3)^2}}}
{{{D^2=9+16}}}
{{{D^2=25}}}
{{{D=5}}}
So then the perimeter is just the sum of all of these lengths,
{{{P=6+4+3+5}}}
{{{P=18}}}