The perimeter of the triangle is 6a + 3 units. Write an expression in simplest form for the length of Side 3.

Answer:
Side 3 = a - 2
Step-by-step explanation:
Perimeter of a ∆ = sum of all the sides of a triangle
Perimeter of the given ∆ = 6a + 3 units
Side 1 = 2(a + 3)
Side 2 = 3a - 1
Side 3 = ?
Therefore:
Side 3 = Perimeter - sum of side 1 and 2
Thus:
Side 3 = 6a + 3 - [2(a + 3) + (3a - 1)]
Side 3 = 6a + 3 - [2a + 6 + 3a - 1]
Side 3 = 6a + 3 - [5a + 5]
Side 3 = 6a + 3 - 5a - 5
Side 3 = a - 2
The length of the third side is a-2.
Given that:
Perimeter of triangle: 6a + 3
Length of first side: 2(a+3)
Length of second side: 3a -1
Let the length of the third side of the triangle be x.
Then as perimeter of a triangle is sum of lengths of all 3 sides of the triangle, thus we have:
[tex]2(a+3) + x + 3a -1 = 6a + 3\\\\x = 6a - 2a - 3a + 3 - 6 + 1\\\\x = a - 2[/tex]
Thus we have length of the third side as a -2.
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