46.1. Through the midpoint $K$ of the side $A B$, draw a line parallel to $C D$ (Fig. 11). Denote the points of intersection of this line with the lines $A D$ and $B C$ as $M$ and $P$, respectively. Based on the equality of triangles $A K M$ and $B K P$, we conclude that the trapezoid $A B C D$ is equal in area to the parallelogram $M P C D$. Since the area of the parallelogram is $m n$, the area of the trapezoid will also be $m n$.

![](https://cdn.mathpix.com/cropped/2024_05_21_f0d089db3d527e92a992g-25.jpg?height=334&width=529&top_left_y=907&top_left_x=775)

Fig. 11
46.1. In trapezoid $ABCD$, the lateral side $CD$ is equal to $m$, and the distance from the midpoint of side $AB$ to the line $CD$ is $n$. Find the area of the trapezoid.