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What is the Perimeter of Triangle GHF? 325 Views
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Description:
ACT Math: Plane Geometry Drill 2, Problem 2. What is the perimeter of triangle GHF?
Transcript
- 00:02
Here's your shmoop du jour: What is the perimeter of triangle GHF?
- 00:07
And here are the potential answers...
- 00:12
First let's be clear that it's THIS triangle we're talking about -- so....why would
- 00:16
the question SHOW us all this other stuff?
- 00:18
Hm...
Full Transcript
- 00:19
Yeah. Well -- FGH and FDE are SIMILAR triangles -- that is, all their angles are equal, and
- 00:25
GH is parallel to DE.
- 00:26
How do we know? Well, since the two triangles are SIMILAR, it means that the perimeter edges
- 00:27
must parallel.
- 00:27
Start by finding the perimeter of triangle FDE...
- 00:30
We get 8 plus 2 plus 6 plus 2 plus 8... which is 26.
- 00:35
We want to find GH and we know that GH is proportional to DE.
- 00:40
So we can write FG is to FD, or 8 is to 10, as GH is to DE -- and DE is 6... so we get
- 00:44
the ratio 8 is to 10 as GH is to 6.
- 00:47
Cross-multiply and we get 48 equals 10 times GH... so the distance GH is 48 over 10...
- 00:55
or 4.8.
- 00:56
Now we have to just add the perimeter sides of 8 and 8 which is 16; add to 4.8 and we
- 01:04
get 20.8 as the perimeter for triangle GHF.
- 01:07
Answer D.
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Curious to find out what angle these guys are playing? Check out this video. You’ll have angles coming out of the wazoo.
We know what you came here for—you want to hear the latest interview with the hot starlet, Polly Gon. Well, we've got the scoop for you. She's re...