Question

use the surface area and lateral area formulas to find the area of the prism.

Answer 1

u have the LA, SA formulas ?

Answer 2

LA=ph
SA=LA+2B

Answer 3

yes, start by finding LA first

Answer 4

how do i do that with this shape?

Answer 5

First figure out wat \(base\) and \(height\) are

Answer 6

\(base\) is octagon wid side of 5cm
\(height \) = 22cm

Answer 7

can u find the perimeter of base

Answer 8

110 cm^2

Answer 9

perimeter is the length around shape

Answer 10

perimeter = 5 x 8 = 40

Answer 11

LA = ph
= 40 x 22

Answer 12

oh ok

Answer 13

wat about SA

Answer 14

SA=880+2B

what do i put for the 'B'

Answer 15

B = area of octagon

Answer 16

oh so how do i find that

Answer 17

Area of regular polygon wid sides \(n\) , = \(\large \frac{n}{4}s^2\cot (\frac{180}{n})\)

Answer 18

u must be having this formula in ur notes ?

Answer 19

ah yes

Answer 20

Area of regular octagon wid sides \(8\) , = \(\large \frac{8}{4}*5^2\cot (\frac{180}{8})\)

Answer 21

76.3190555774

Answer 22

try again

Answer 23

76.3

Answer 24

looks wrong

Answer 25

http://www.wolframalpha.com/input/?i=8%2F4*5%5E2+*+cot+%28180%2F8%29&a=TrigRD_D

Answer 26

u should get B = 120.7

Answer 27

yea i see now

Answer 28

good, multiply it wid 2 and add to LA

Answer 29

SA=880+241.4
SA=1121.4

Answer 30

\(\large \color{red}{\checkmark}\)

Answer 31

thanks @ganeshie8