# Square pyramids.

Posts: 7967
Joined: March 8, 2006

If the height of a square pyramid is 10 m and the surface area of one side is 50. What's the perimeter of the base.

Posts: 423
Joined: Sept. 26, 2005

is that slant height or peak height from the base plain?

EDIT:
If its slant height is 10m its 40m

SA=bl/2 l=slant height b=base length SA=surface area
SA=50
50=(b10/2)
b=10

bx4=perimeter
10x4 is 40

peak height 10 answer is 37.7124

a2 + b2 = c2
100 + B2 = l
100 = bx2

50= AB
b=A/2

Sqaure root of 50= A or B
A=7.071
7.071/2
b=3.5355
now put b into Pythagorus

100 + (3.5355 Squared) =c(squared)
100 + 12.49976 = 112.49976
(root)112.49976 = 10.60659
c=10.60659
c=l
l=10.60659

SA=bl/2 l =slant height b=base length SA=surface area
SA=50
50=b10.60659/2 multiply by 2 to remove the divisor
100=b10.60659
b=9.4281

b4=perimeter
9.4281x4 =
37.7124

Sorry if it doesn't make sense, but Im in the car on my way to sea otter and we are looking for a motel for the night.

**Big thanks to:

Morpheus Cycles
Industry Nine Componentry
RaceFace
- Velocity Cycles - **

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Joined: May 29, 2004

Sorry if it doesn't make sense, but Im in the car on my way to sea otter and we are looking for a motel for the night.

Judging by your calculations,I'd say you found one.

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Joined: Aug. 4, 2009

Posts: 15557
Joined: May 29, 2004

I'm actually kinda impressed that we have a mobile mathematician on hand at 1 am to solve our problems for us.

Posts: 13934
Joined: March 15, 2003

I'm actually kinda impressed that we have a mobile mathematician on hand at 1 am to solve our problems for us.

golf clap Posts: 7967
Joined: March 8, 2006

is that slant height or peak height from the base plain?

EDIT:
If its slant height is 10m its 40m

SA=bl/2 l=slant height b=base length SA=surface area
SA=50
50=(b10/2)
b=10

bx4=perimeter
10x4 is 40

peak height 10 answer is 37.7124

a2 + b2 = c2
100 + B2 = l
100 = bx2

50= AB
b=A/2

Sqaure root of 50= A or B
A=7.071
7.071/2
b=3.5355
now put b into Pythagorus

100 + (3.5355 Squared) =c(squared)
100 + 12.49976 = 112.49976
(root)112.49976 = 10.60659
c=10.60659
c=l
l=10.60659

SA=bl/2 l =slant height b=base length SA=surface area
SA=50
50=b10.60659/2 multiply by 2 to remove the divisor
100=b10.60659
b=9.4281

b4=perimeter
9.4281x4 =
37.7124

Sorry if it doesn't make sense, but Im in the car on my way to sea otter and we are looking for a motel for the night.

That's overal height not slope height

Posts: 547
Joined: Aug. 30, 2010

I wanted to say 40 at first as well, with the it's probably a trick question answer, but I gotta agree with Mitch as it is worded.

Also, the plane will take off.

Posts: 3775
Joined: Nov. 19, 2002

n(2n - 2) = n(2n - 2)
n(2n - 2) - n(2n - 2) = 0
(n - n)(2n - 2) = 0
2n(n - n) - 2(n - n) = 0
2n - 2 = 0
2n = 2
n + n = 2
or setting n = 1
1 + 1 = 2

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