Exactly as you do using a physical straightedge, compass and protractor.
@robocompass I'm impressed with your rather beautiful interface!
@robocompass - this looks so good!
"A day long MathDisk and Robocompass workshop was conducted by co-founder Rafiq Jaffar Ali on 23-06-2014 at NASA's Langley Research Center,Virginia."
Institution of Engineering and Technology, Europe's largest professional organization in the field of secondary education.
MathDisk Technologies is a Gess Education Award 2015 finalist on "Best Free ICT App category" Robocompass is developed by MathDisk Technologies.