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Triangle ABC is isosceles with AB = BC. If AC = 20 and [ABC] = 240, then find the perimeter of triangle ABC. Solve using Heron's Formula.

 May 19, 2020
 #1
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+1

first of all, i also dont understand who heron is.
but idc about heron, I can solve it without heron
..
look dude, we are gonna get the perimeter by this:
sorry i did not have any geometrical materials, hope u dont think its a slice of pizza!

guys, this took me ages, so give me a like, heart and remember to turn on notification to get the latest answer! wink

 May 19, 2020
 #2
avatar+111456 
+1

Let AB  =  BC  =   x

 

The semi-perimeter  =    ( 2x  + 20)  /  2    =  x + 10     =   s

 

Using Heron's

 

Area^2  =  s  ( s - x) ( s - x) ( s -  20)

 

240^2  = (x + 10) ( 10) ( 10) (x - 10)

 

240^2  =  100 ( x^2  - 100)

 

240^2 /100  =  x^2 - 100

 

576  =  x^2  - 100

 

676  =  x^2        take the positive root

 

26   =   x

 

The perimeter  =   2x + 20   =    2(26) + 20   =   52 +  20   =   72

 

 

cool cool cool

 May 19, 2020
 #3
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i dont understand what u said, cphill, its complicated.. 

mine is way more clear! heron's formula is tough.. 
how did u memorize it all cphill? tell meeeeeeeeee!

Guest May 19, 2020

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