SOLUTION: The first side of a triangle is 9m shorter than the second side. the third side is 3 times as long as the first side.the perimeter is 39m. find the length of the longest side.

Question 362138: The first side of a triangle is 9m shorter than the second side. the third side is 3 times as long as the first side.the perimeter is 39m. find the length of the longest side.
Answer by HasanSahin(52) (Show Source): You can put this solution on YOUR website!

let's say the first side is a,the second side is b and the third is c.
a = b-9 (1) and 3a = c (2) and perimeter a + b + c = 39 (3)
put "a" in 1st equation to 2nd equation >>> 3*(b-9) = c >> 3b - 27 = c (4)
put "a" in 1st equation to 3rd equations also >> b-9+b+c = 39 >> c = 39-2b+9 (5)
put "c" in 5th equation to 4th equation >> 3b-27 = 48-2b >> 5b = 75 >> b = 15

Solve 1st equation >> a = 15-9 >> a = 6
Solve 3th equation >> 6 + 15 + c = 39 >> c = 18.
Therefore longest side is c, c=18.
RF.
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