1. The diagram shows a solid prism $ABCDEFGH$.

The trapezium $ABCD$, in which $AD$ is parallel to $BC$, is a cross section of the prism.
The base $ADEH$ of the prism is a horizontal plane. $ADEH$ and $BCFG$ are rectangles.
The midpoint of $BC$ is vertically above the midpoint of $AD$ so that $BA=CD$.

$AD=37cm$   $GF=28cm$    $DE=24cm$

The perpendicular distance between edges $AD$ and $BC$ is 20 $cm$.

Calculate the size of the angle between $AF$ and the plane $ADEH$.
Give your answer correct to one decimal place.