A circle is a collection of points all of which are on the circumference of the circle. If you use algebra and (x-h)^2 + (y-k)^2 = r^2 and the info contained in the coordinates (x,y) of each city, you can find h, k and r. Then r is the (equal) distance between each city and the center of the circle, where the new tower will be built.
Step 1: Create an equation with a slope of 6
y=6x+b
Step 2: Substitute x and y by with the point (1,2) and solve the equation for b
y=6x+b
2=6(1)
2=6
2=6+b
b=-4
Step 3: Substitute -4 for b in the equation
y=6x+b
y=6x+(-4)
y=6x-4
The equation that has a slope of 6 and passes through the point (1,2) in point-slope form:
y=6x-4
The 5 represents the starting distance from home. In other words, when t = 0, the value of y is y = 5. Replacing t with 0 leads to this y value. This is the y intercept. So at time 0 minutes, the ant is 5 units from home. Replace "units" with whatever units you happen to be using.
C= 2pi
15= diameter. Radius= 15/2. R= 7.5
C= 2 times pi times 7.2
C=15 pi
C= 47.1
