The altitude of a pyramid is 30 cm and its base is enclosed by arectangle whose dimensions are 12 cm by 18 cm, respectively. What is the distance from the vertex of a section parallel to the base whose whose are is 72 squared cm?

Solution:

Base area = 12*18 = 216 square cm

The proportion of the section area to base area = 72/216 = 1/3

So the distance / Altitude = sqrt(1/3)

the distance = sqrt(1/3)*Altitude = sqrt(1/3)*30 = 17.32 cm