ErinWeeks
Find the surface area of the figure to the nearest whole number.
PLEASE HELPPPP
Delete
Share
This Question is Closed
ErinWeeks
Best Response
You've already chosen the best response.
0
A. 310 ft2
B. 158 ft2
C. 135 ft2
D. 74 ft2
I thought it was C but it was wrong -_-
ankolix
Best Response
You've already chosen the best response.
1
the back side in the image is very confusing :/
ErinWeeks
Best Response
You've already chosen the best response.
0
its 2.5 and 3.3
JayDS
Best Response
You've already chosen the best response.
1
hint: split it into two objects. find the surface area of the top triangle pyramid and add it to the surface area of the square prism
ErinWeeks
Best Response
You've already chosen the best response.
0
im still confused
JayDS
Best Response
You've already chosen the best response.
1
but you understand what I said?
ErinWeeks
Best Response
You've already chosen the best response.
0
i dont really -_-
JayDS
Best Response
You've already chosen the best response.
1
k wait, let me work through the whole thing first then I'll explain it to you.
ErinWeeks
Best Response
You've already chosen the best response.
0
okay thank you
JayDS
Best Response
You've already chosen the best response.
1
|dw:1357770316535:dw|
see I split the two? this is what I meant and excuse my drawing.
Note: we do not need to find the bottom base of the pyramid and top of the square prism, as it is not accounted towards the total surface area. (It's the part where they are glued together if you may).
ankolix
Best Response
You've already chosen the best response.
1
well i can to see 2 solids... the piramid and the cube.. so the piramid area is \[\frac{ 1 }{ 2 }* perimetre*face length\]. in your piramid \[\frac{ 1 }{ 2 } \times 18\times 3.3 \] and the cube surface
ErinWeeks
Best Response
You've already chosen the best response.
0
for the second formula i got 29.7 ... i dont know how to do the 1st one
JayDS
Best Response
You've already chosen the best response.
1
yes 29.7 is right for the top(pyramid).
ErinWeeks
Best Response
You've already chosen the best response.
0
okay now can you explain how to do the bottom
JayDS
Best Response
You've already chosen the best response.
1
for the bottom(square prism) it is even easier.
2(4.5 x 6 + 4.5 x 6) + (4.5 x 4.5)
JayDS
Best Response
You've already chosen the best response.
1
this is because the top of the square prism(where it needs to be used to be stuck against the bottom part of the pyramid) is not accounted for.
ErinWeeks
Best Response
You've already chosen the best response.
0
i got 74.25 now what ??
JayDS
Best Response
You've already chosen the best response.
1
add them together.
JayDS
Best Response
You've already chosen the best response.
1
to get your final answer.
ErinWeeks
Best Response
You've already chosen the best response.
0
i got 103.95 but thats not a choice
JayDS
Best Response
You've already chosen the best response.
1
your 74.25 you got is wrong, try again.
JayDS
Best Response
You've already chosen the best response.
1
it should be 128.25
ankolix
Best Response
You've already chosen the best response.
1
no, it is \[4(4.5*6)+ 2(4.5*4.5)\]
ErinWeeks
Best Response
You've already chosen the best response.
0
with @ankolix formula i got 142.5
JayDS
Best Response
You've already chosen the best response.
1
@ankolix I don't think you understand the concept that you only need 4.5 x 4.5 once not twice.
ErinWeeks
Best Response
You've already chosen the best response.
0
@JayDS my answer and your answer are both not an option
ankolix
Best Response
You've already chosen the best response.
1
yeah.. ivemistake
JayDS
Best Response
You've already chosen the best response.
1
please tell me the options.
ErinWeeks
Best Response
You've already chosen the best response.
0
A. 310 ft2
B. 158 ft2
C. 135 ft2
D. 74 ft2
JayDS
Best Response
You've already chosen the best response.
1
and you made a calculation error before, so please be careful when entering it in the calculator.
ankolix
Best Response
You've already chosen the best response.
1
is 4(4.5*6)+(4.5*4.5)+29.7=157.95.. option B
JayDS
Best Response
You've already chosen the best response.
1
yep, option B.
JayDS
Best Response
You've already chosen the best response.
1
using my calculation you will get 157.95. and why is it not exact? because probably when they calculated they used more decimal places which resulted them to get a more accurate answer but we have been only given that, so we just those figures in the picture.
ankolix
Best Response
You've already chosen the best response.
1
medal for gratitude ;)
ErinWeeks
Best Response
You've already chosen the best response.
0
okay thank you so muchh..
JayDS
Best Response
You've already chosen the best response.
1
@ankolix, I would like to say you deserve the medal for trying but you have copied off me but good job.