Question

An isosceles triangle has at least two congruent sides. The perimeter of a certain isosceles triangle is at most 12 in. The length of each of the two congruent sides is 5 in. What are the possible length of the remaining side?

A. s >= 5 but less than 12
B. s <= 12 but greater than 0
C. s <= 10 but greater than 0
D. s <= 2 but greater than 0

Answer 1

The length of one of the congruent side is 5
The total length of two congruent sides is 10

Perimeter at the most is 12 (meaning the maximum length of perimeter is 12) 
The third side of the triangle must be 12-10 = 2 at the most

Writing this requirement as inequality we have
$x \leq 2$ but must be greater than 0

Answer: D