Question

PLZ HELP
The volume of a frustum of a pyramid is 360 and its height is 12. If the area of one base is 10, what is the area of the other base

Answer 1

Given :

The volume of frustum of a pyramid = 360

Height = 12cm

Area of base(a²) = 10

To find :

The area of other base = ?

Solution :

• volume of frustum of a pyramid = (h/3) [a²+ab+b²]

• (h/3) [a²+ab+b²] = 360

       (12/3) [10+√10b+b²] = 360

      4× [10+√10b+b²] = 360

      10+√10b+b² = 90

     b²+√10b-80 = 0

• By solving the above quadratic equation

     b = (√10+√330) / 2

     b = 7.5

     b² = 56.25 cm²

  The area of other base is 56.25 cm²