Math Problem Statement

solve

What is the surface area of this triangular pyramid?

Solution

To find the surface area of the triangular pyramid, we need to calculate the area of all its triangular faces and sum them up.

Given Information:

  1. Base Triangle Dimensions:

    • Each side of the base triangle is 9m9 \, \text{m}.
    • The height of the base triangle is not given explicitly, so we'll calculate it using the formula for the height of an equilateral triangle.

    Height=32side length=329=7.8m.\text{Height} = \frac{\sqrt{3}}{2} \cdot \text{side length} = \frac{\sqrt{3}}{2} \cdot 9 = 7.8 \, \text{m}.

    Area of the base triangle: Area=12baseheight=1297.8=35.1m2.\text{Area} = \frac{1}{2} \cdot \text{base} \cdot \text{height} = \frac{1}{2} \cdot 9 \cdot 7.8 = 35.1 \, \text{m}^2.

  2. Three Lateral Triangles:

    • Each lateral triangle has a base of 9m9 \, \text{m} and height of 6m6 \, \text{m} (as indicated in the image).
    • Area of each lateral triangle: Area=12baseheight=1296=27m2.\text{Area} = \frac{1}{2} \cdot \text{base} \cdot \text{height} = \frac{1}{2} \cdot 9 \cdot 6 = 27 \, \text{m}^2.
    • Total area of the three lateral triangles: 327=81m2.3 \cdot 27 = 81 \, \text{m}^2.

Total Surface Area:

Total Surface Area=Base Area+Lateral Areas=35.1+81=116.1m2.\text{Total Surface Area} = \text{Base Area} + \text{Lateral Areas} = 35.1 + 81 = 116.1 \, \text{m}^2.

Final Answer:

116.1square meters\boxed{116.1 \, \text{square meters}}

Do you want additional details or have any questions? Here are some follow-up topics:

  1. How to derive the formula for the height of an equilateral triangle.
  2. Why the lateral faces are considered congruent.
  3. How to calculate the surface area of pyramids with different base shapes.
  4. How to compute the volume of this pyramid.
  5. How scaling the dimensions affects the surface area.

Tip: Always check if the base is equilateral or irregular before proceeding with calculations.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Surface Area
Geometry of Triangular Pyramids

Formulas

Area of a triangle = (1/2) * base * height
Height of an equilateral triangle = (sqrt(3)/2) * side length

Theorems

Properties of equilateral triangles
Properties of triangular pyramids

Suitable Grade Level

Grades 9-10