Question

a triangle pyramid with an equilateral base has a side length of 10 centimeters and a surface area of 214.5 square meters. find its slant height

Answer 1

area of the base = 1/2 * 10 *  5sqrt3 =  25 sqrt3

Total surface area = 25 sqrt3 + 3 *  1/2 * 10 * slant height = 214.5

25 sqrt3 + 15h = 214.5
15h = 214.5 - 25 sqrt3

h =   (214.5 - 25sqrt3() / 15

=  11.41 cm to nearest hundredth