Explanation:
the slant height of the pyramid is the height of any of the 4 triangles that are the sides (faces) of the pyramid.
it is not clear, if the given area information is the total area of all 4 faces together, or of each individual side.
normally, I would take the first option, but to be on the safe side I will do both calculations.
remember, the area of a triangle is
baseline × height / 2
we know the length of the baseline (35 m) and the area.
out of this we will calculate the height.
option 1
the area of all 4 sides together is 1,442 m².
that means the area of one side (face) is
1442 / 4 = 360.5 m²
that gives us
360.5 = 35 × height / 2
721 = 35 × height
height = slant height of the pyramid = 721/35 = 20.6 m
option 2
the area of any one of the 4 sides is 1,442 m².
that gives us
1442 = 35 × height / 2
2884 = 35 × height
height = 2884/35 = 82.4 m
realistically, that is not the case and too large.
so, option 1 is the correct answer.