Help finding a tree's diameter

To convert circumference to diameter we need to remember the formula for circumference. Circumference = 2 * pi * r. r is the radius. Using the distributive property C = pi*2*r. 2 * r is the diameter. Substituting diameter for 2*r we have C = Pi*diameter. Dividing both sides by pi we have C/pi = diameter. To find the diameter we divide the circumference by pi. You can do that with your pocket calculator or use this JavaScript calculator.