Triangle peremiter question. Please help!

Question

One side of a triangle has length of 12cm and the second side is 3cm longer than the third side. Find the lenth if the perimeter is 72cm.

Answer 1

Hi Luise,

 

Let x = lenght of the third side

 

then the second side is x + 3      (second side is 3cm longer than third side

 

and the perimeter is the some of the sides

 

so

 

P = 12 + x + x +3   (where 12 is one side, x is the third side and x+3 is the second side

 

and we know that P is 72

 

72 = 12 + x + x +3

 

2x = 57

 

x = 28.5

 

x + 3 = 31.5

 

so the three sides are 12, 28.5 and 31.5  and they add up to 72

 

Hope this helps