Question

i dont get the 3 diffrent numbers ?


Find the surface area of the pyramid.

Answer 1

A. 412cm2
B. 419cm2
C. 423cm2
D. 445cm2

Answer 2

you have width, and length of the base; and a slant height (height of a triangle face)

Answer 3

im not sure if they meant for the 15 to be for all sides, or if you have to find the slant height for the 9

Answer 4

so, how much of this have you been able to determine on your own?

Answer 5

Im not sure , ?

Answer 6

well, lets start by defining surface area; it is the area of ALL sides.

we have 5 sides to account for

base, is a rectangle

2 triangles of 15 by 12

and 2 triangles of * by 9

Answer 7

finding the * value is the only real tricky part of this

Answer 8

let get the easy ones out of the way,

do you know how to find the area of a rectangle?

Answer 9

L x W

Answer 10

good, and those are given as 12 and 9, what is 12*9?

Answer 11

108

Answer 12

lets write that down to remember it and move on to the next easy part

2 triangles that are 15 by 12

how do we find the area of a triangle?

Answer 13

Base x Height / 2 ?

Answer 14

correct, and since there are 2 of them of the same measures; let mulitply that by 2

2 * (15*12)/2 = 15*12 , what is 15*12?

Answer 15

180

Answer 16

good, so far we have determined an area of 108 + 180 = 288

just 2 more surfaces to go, and this is where it gets tricky; but, its doable

Answer 17

do you recall the pythag thrm? a^2 + b^2 = c^2?

Answer 18

yeah

Answer 19

im thinking we can use that to find "h" in this drawing.

first we need to find the "edge" that they have in common tho.