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Define variables for the side lengths.
Perimeter: 67.5 inches
Explanation: See solution.
Consider that the ratio of the side lengths of a triangle is 2:3:4. We want to find the perimeter of the triangle if the shortest side is 15 inches. To do so, let's start by define the side lengths.
This means that the ratio x:y is equal to ratio of the shortest and longest side, 2:4. The same will occur with the value of the ratios.
x/y=2/4
x= 15
LHS * y=RHS* y
a/y* y = a
a/c* b = a* b/c
LHS * 4=RHS* 4
a/4* 4 = a
Multiply
.LHS /2.=.RHS /2.
Cancel out common factors
Simplify quotient
Rearrange equation
This means that the longest side in the triangle is 30 inches long. Now we can use a similar procedure for the third side. This time the ratio z:y will be equal to the ratio of the middle side and the longest side. z/y=3/4 The longest side of the triangle is y= 30. Let's substitute this value into the equation and solve for z.
y= 30
LHS * 30=RHS* 30
a/30* 30 = a
a/c* b = a* b/c
Multiply
Calculate quotient
The middle side is 22.5 inches long. Finally, let's calculate the perimeter by adding the three side lengths. P=15+30+22.5 → P=67.5 The perimeter of the triangle is 67.5 inches.