A full turn around a point equals 360º. If a full turn equals 360º, then the sum of the angles around a point must also be 360º. When you calculate angles around a point, you can use this fact to find ...

I'm reading Randall Munroe's book How To: Absurd Scientific Advice for Common Real-World Problems. I probably don't have to tell you this, but it's awesome (as is everything from Randall Munroe, the ...