Figure 038: From a given point B, in a given line AB, to construct an angle equal to a given angle C.

11. From a given point B, in a given line AB, to construct an angle equal to a given angle C.

From point C of the given angle as centre, and with any radius, draw the arc EF : and with the same radius, with B as centre, draw the arc GH ; take the length of the arc EF, and set it off on GH ; draw the line BD through H. Then the angle GBH will be equal to the given angle C.