From Triangle Inequality Theorem
The sum of any 2 sides of a triangle must be greater than the measure of the third side.
The sum of 2 sides is less than (or equal to) the measure of a third side.
In an isosceles triangle, two sides are equal.
Then we have an option the third side= 8. Let's analyze!
c+a> b - for a and c =8
8+8 > 10
16> 10
The second option is the third side= 10. Let's analyze!
c+a> b - for a and c =10
10+10> 8
20> 8
Answer
A. either 8 or 10