we have the length sides
15,12,9
Remember that
The Triangle Inequality Theorem states that the sum of any two sides of a triangle must be greater than the measure of the third side
You only need to see that the two smaller sides are greater than the largest side
so
12+9 > 15
21 > 15 -----> is true
that means
the answer is
YES, the following sides can make a triangle
