GreenlightTestPrep wrote:
The lengths of two sides of isosceles triangle XYZ are 8 and 18.
Quantity A |
Quantity B |
The perimeter of triangle XYZ |
36 |
Key property : If two sides of a triangle have lengths A and B, then . . . the DIFFERENCE between A and B < length of third side < the SUM of A and BSince an isosceles triangle has two the sides of equal length, there are two possible cases to consider:
case i: The three sides have lengths 8, 18 and 18
case ii: The three sides have lengths 8, 8 and 18
Important: case ii breaks the above
property.
If we let the side with length 18 be the third side, we get:
8 - 8 < 18 < 8 + 8Simplify to get:
0 < 18 < 16, which is not true.
So, case ii is impossible
Case i meets the above
property, so the sides must have lengths 8, 18 and 18, which means the perimeter = 8 + 18 + 18 =
44Answer: A