Using the knees of the giver as a vertex point, look at the angle between the giver and the surface the receiver is lying on.If the giver is supporting himself via his arms, then most likely it is the missionary position.
It can sometimes be hard to distinguish between deep stick and missionary, so there are some characteristics one can look for to differentiate the two: The missionary position is similar to the deep stick position except in the deep stick position the giver is not laying on top of the receiver the giver is mostly kneeling.
