Example Calculate the circumference of the dartboard. The diameter is twice the radius. d = 20 × 2 = 40 cm Circumference = 40 × π = 125.7 cm (1 decimal place).

Let’s say we have a circle with a radius of exactly that size (or 25 billion miles in diameter) and we want to calculate the circumference, which is pi times the radius times 2.

Calculate the circumference of the Earth using this equation: Circumference = 360 x distance between your city and the equator / angle of shadow that you measured What value do you get?

Estimating a Tree's Age by Species Begin by determining the tree species and taking a diameter measurement (or convert circumference to a diameter measurement) using a tape measure at diameter ...