If the lateral surface area of a square pyramid is 84ft^2 and the base edge is 6, what is the slant height?

The slanting height of the pyramid will be calculated as follows;
lateral area is given by:
Area=[area of the base]+4[area of triangular sides]
area of the base will be:
Area=length*width
=6*6=36 ft^2
area of triangular sides will be:
[84-36]
=48 ft^2

area of one triangle will be:
48/4=12 ft^2
but
area of triangle is given by:
area=1/2bh
hence the height will be:
12=1/2*6*h
12=3h
h=12/3
h=4 ft
the answer is 4 ft

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