check the picture below.
make sure your calculator is in Degree mode.
The surface area formula for any sphere is 4(pi)(radius)^2
The radius is half of the diameter.
18.6 / 2 = 9.3
So, plug into the formula and solve.
4(3.14)(9.3)^2 = 1086.3 mm^2
It's angle B, the dashed lines show what lines are equal to each other and the 1 dash and 2 dash both go into angle X and angle B
Y = -5x +18
x can be any number, y can be change due to x value