A pyramid has a square base of 6 cm, and the four lateral faces are four congruent equilateral triangles. What is the total surface area of the pyramid in square cm?	Answers: A) 36 + 18*sqrt(3) B) 36 + 36*sqrt(3) C) 72 D) 72 + 36*sqrt(3) E) 72 + 72*sqrt(3)
First of all, of course, the base has an area of 36. For the lateral surfaces, it would be helpful to remember the formula for the area of an equilateral triangle.   The area of one equilateral triangle is A = (s^2*sqrt{3})/4. We know the side of the equilateral triangle must be the same as the square: s = 6. Thus, one of these equilateral triangles has an area of A = (6^2*sqrt{3})/4 = 9*sqrt{3}. There are four identical triangles, so their combined area is A = 36*sqrt{3}. Now, add the square base, for a total surface area of A = 36 + 36*sqrt{3}. Answer = 36 + 36*sqrt(3)
<result>B</result>
A pyramid has a square base of 6 cm, and the four lateral faces are four congruent equilateral triangles. What is the total surface area of the pyramid in square cm?