A pyramid composed of four equilateral triangles, called a tetrahedron, has a one-side length of 5 meters. What is its surface area? Round the answer to the nearest tenth.
The area of an equilateral triangle is (1/2)bh. The base is 5, so using the Pythagorean theorem we get h by: 5² = (5/2)² +h² h = √18.75 h = 4.33 So the area of one face is (1/2)(5)(4.33) = 10.825m² The total area is 4(10.825m²) = 43.3m²
