# How to Copy an Angle Using a Compass

The basic idea behind copying a given angle is to use your compass to sort of measure how wide the angle is open; then you create another angle with the same amount of opening.

Here’s the proof diagram.

Refer to the figure as you work through these steps:

**Draw a working line,***l*, with point*B*on it.**Open your compass to any radius***r,*and construct arc (*A*,*r*) intersecting the two sides of angle*A*at points*S*and*T.***Construct arc (***B*,*r*) intersecting line*l*at some point*V.***Construct arc (***S*,*ST*).**Construct arc (***V*,*ST*) intersecting arc (*B*,*r*) at point*W.***Draw line***BW*and you’re done.