Question

The perimeter of the base of the regulr triangular pyramid is p=16.5cm find the sum of all edges of this pyramid if the perimeter of a lateral face is 18.5cm

Answer 1

Sum of all edges = 36 cm

Explanation:

When calculating the sum of the perimeters of three lateral faces, we will end up counting each "lateral" edge twice and the base edges once due to the shape of the way a pyramid appears.

Now, if we add the base perimeter to the sum above, it means we would have counted every edge twice.

Thus, the total of all edge lengths is given as;

(3(18.5) + 16.5)/2 = 72/2 = 36 cm

Answer 2

36cm

Explanation:

The addition of the perimeters of three lateral faces will count each "lateral" edge will be twice and the base edges will be counted once. Adding the base perimeter to the product will count every edge twice, so the total of all edge lengths will be as follow:

(3×18.5 cm +16.5 cm) ÷2 =

(55.5cm +16.5)/2

72 cm/2 = 36 cm

sum of all edge lengths will be 36cm