Level 11: Construct an angle on the given line equals to the given angle

Hint: Reproduce triangle with specified length and base

Solution: In the last level we already know how to reproduce a triangle with specified length and base. This is only another instance of it. Reproduce the triangle ABC with the given line D as base would solve the problem. Specifically, draw circle with center D with radius AB, mark the intersection point K. Draw circle with center D and radius AC, and draw circle with center K and radius BC. Draw the ray from D to the new intersection point L and we are done.