Question

Hi! I need surface area help again >.< Can you help me through the process of getting the answer?

Answer 1

do they say that the bottom is an equilateral triangle ?

Answer 2

Yes, its an equilateral triangular based pyramid

Answer 3

the surface is made of 4 triangles: 3 "sides" and the bottom

the area of a triangle is 1/2 * base * height

so the job is identify the base and height of the 4 triangles, find their area, and add it up

Answer 4

How do I find the base?

Answer 5

of which triangle ?

Answer 6

the bottom triangle is equilateral meaning all 3 sides are the same length, namely 12

Answer 7

so its 1/2 * 12 * 14.4?

Answer 8

they show an altitude for the bottom triangle, 10.4

so you can find the area of the bottom

Answer 9

all 3 "sides" are the same size, with base 12, and height 14.4

Answer 10

So I multiply the product of that by 3?

Answer 11

yes, the total of the 3 sides is 3/2 * 12*14.4
then add in the bottom: 1/2 * 12 * 10.4

Answer 12

148.8?

Answer 13

km^2

Answer 14

I get 321.6

Answer 15

wait its suppose to be 3/2 instead of 1/2 for the 3 sides?

Answer 16

the 3 "sides" each have area 1/2 * 12 * 14.4

so the area of all 3 together is 3 * 1/2 * 12 * 14.4 which I wrote
as 3/2 * 12 * 14.4

Answer 17

that gives 259.2

now add the bottom : 1/2 * 12 * 10.4

Answer 18

Ohh, now I got 321.6

Answer 19

(3 * (2 / (12 * 14.4))) + ((2 / (12 * 10.4)))

Answer 20

Good. I would think it over, to see if it makes sense, and try to remember how to solve the next problem that is like this one.

Answer 21

I will, I have like 3 more :D Thanks Phi!

Answer 22

required area=1/2*12*10.4+3*1/2*12*14.4
=62.4+3*86.4
=62.4+259.2=321.6 sq.km

Answer 23

Thanks :D