A full circle is 360 degrees.
You are given the angles for GH, HE and FE, subtract those from 360 to find the angle for FG:
360 - 110 - 80 - 40 = 130 degrees.
Now for the arc GFE add FG and FE:
Arc GFE = 130 + 110 = 240 degrees.
Circumference = 2 x PI x r
Using 3.14 for PI:
Circumference = 2 x 3.14 x 5 = 31.4 mm or 10PI
Area = PI x r^2 = 3.14 x 25 = 78.5 mm^2 or 25PI mm^2
Equation of a circle with center at (-1,2) and diameter of 12:
The equation is written as (x-x1)^2 + (y-y1)^2 = r^2
x1 and y1 are the values of the center (-1,2) and r is the radius, which would be half the diameter.
The equation is: (x+1)^2 + (y-2)^2 = 36