Question

geometry help. http://is.byu.edu/courses/hs/GEOM-043-101/secure/imgs/math10-2305.gif

Answer 1

Calculate the surface area of a regular triangular pyramid with the base edges of length 12 and a slant height of 12. (Hint: Remember that the base of a regular triangular pyramid must be an equilateral triangle, not necessarily congruent to the sides of the pyramid.)

Answer 2

Hint: Count the surfaces and find the area of each sides.

Answer 3

http://hotmath.com/hotmath_help/topics/surface-area-of-a-pyramid.html

lateral surface area (the 3 sides) is = p*s/2 where p is the perimeter of the base and s is the slant height.

Answer 4

yea thats wat i got but i wasnt sure

Answer 5

can u guys help me in one more question

Answer 6

plz

Answer 7

the area of the bottom is the area of an equilateral triangle
sqrt(3)*a^2/4 where a is the length of 1 side

Answer 8

Approximate the volume of the regular triangular pyramid in problem 12 if the height is approximately 11.5. (Hint: Remember that the base of a regular triangular pyramid must be an equilateral triangle, not necessarily congruent to the sides of the pyramid.)

Answer 9

thats another question ^^

Answer 10

I did not get 288. I got 278.35 rounded to 278

Answer 11

y did u get 278. i got 288

Answer 12

the base is an equilateral triangle with sides = 12
so its area is sqrt(3)*12*12/4
see http://en.wikipedia.org/wiki/Equilateral_triangle

Answer 13

the top is 3 * 12*12/2 = 216

Answer 14

SO THE answer is 216?

Answer 15

i did it like this look

Answer 16

the surface area includes the top (3 sides) plus the bottom

Answer 17

SA= A+3/2(SL)
= 72+ (3/2(144)
72+3(72)
72+216= 288

Answer 18

how did you get A= 72?

Answer 19

BASE AREA= 1/2(A)(S)
= 1/2 (12)(12)
1/2(144)
=72

Answer 20

Your questions tells you

(Hint: Remember that the base of a regular triangular pyramid must be an equilateral triangle, not necessarily congruent to the sides of the pyramid.)


that is saying the bottom triangle is an equilateral triangle with 3 sides = 12

the 3 sides on top are not equilateral triangles.

Answer 21

so use the formula for the area of an equilateral triangle for the base A