Answer is below. Look at my explanation to understand my answer.
To see if these lengths can make a triangle, we can use the "triangle side theorem."
The formula is:
a + b > c
a + c > b
b + c > a
So, with that being said...
15 → A
36 → B
39 → C
So, we can use the triangle side theorem by adding A & B, A & C, and B & C.
If the side length is greater than C, B, or A, it can make a triangle. But if it isn't greater than C, B, or A, it cannot make a triangle.
So, let's add 15 and 36 to see if it can make a triangle.
15 + 36 = 51
If you read above, C is 39.
So, 51 > 39
15 + 36 > 39 ✓
Let's repeat this process again.
Instead of C, B is what we're now seeing if the sum is greater than it.
15 + 39 = 54
54 is greater than 36...
54 > 36
So it is true.
15 + 39 > 36 ✓
Now, A is what we're seeing if the sum is greater than it.
36 + 39 = 75
75 is greater than 15...
75 > 15
So it is true.
36 + 39 > 15 ✓
So yes, these lengths can make a triangle.
Let me know of any questions or concerns.