[Intersecting lines, angle between them]

Let $A B C$ be an equilateral triangle, and $B C K M$ be a parallelogram. Find the angle between the lines $A B$ and $K M$.

#
Since $V S K M$ is a parallelogram, line $K M$ is parallel to line $B C$. Therefore, the angle between lines $A B$ and $K M$ is equal to the angle between lines $A B$ and $B C$, i.e., $60^{\circ}$.

## Answer

$60^{\circ}$.