.
Find the surface area of the regular pyramid.
A triangular pyramid. The base triangle has a base of 7 centimeters and a height of 6 centimeters.
The height of a triangular face is labeled 9 centimeters.
~~~~~~~~~~~~~~~~~~~~~~~~
In this problem, surface area is the sum of the area of the base triangle and
the area of three lateral triangle.
The area of any triangle is half the product of the length of its base (= some side) and the length
of the altitude drawn to this side
area = .
For the base triangle, you are given b= 7 cm, h= 6 cm, so its area is
= 7*3 = 21 cm^2.
For three lateral triangles, their areas are equal (since the triangles are congruent).
Using the same rule, you find the area of each triangle = 63/2 = 31.5 cm^2.
So, the total surface are is
21 + 3*31.5 = 115.5 cm^2.
It is the answer to your question.
Solved.