Question 152233
Of course, the sum of the three sides of a triangle is equal to the perimeter.
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Let x = one side of the triangle
x+2 = second side
x+4 = third side
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x + x+2 + x+4 = 45
3x + 6 = 45
3x = 39
x = 13 
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So, the longest side is:
x+4 = 17