The greatest possible value of the perimeter of the triangle is 48
The perimeter of a triangle is the sum of the lengths of the three sides of the triangle.
An isosceles triangle has 2 equal sides and the length of the 2 sides must be greater than the length of one.
Perimeter A= 12×2+18=42
Perimeter B= 12+18×2=48
Therefore the greatest possible perimeter of the triangle is Perimeter B (48) since the sum of lengths of the two equal sides(18) is greater than the third side (12) and 48 is greater than 42.
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