One atmosphere is also the pressure caused by the weight of a column of fresh water of approximately 10.3 m. A diver 25 m underwater experiences a pressure of about 3.5 atmospheres (1 atm of air plus 2.5 atm of water). The added pressure on tom's chest from the water would make inhaling low pressure air from the surface extremely difficult.
As AB and ED are parallel, they have the same slope. This means that since lines that are colllinear with parallel segments are parallel, lines l and m are parallel.
