Hey there!
A (right) triangle can only be constructed if it can be verified by the Pythagorean Theorum.
Basically, the Pythagorean Theorum is the sum of both legs squared need to be equivalent to the hypotenuse (side across from the 90 degree angle) squared.
Let's try our sides as 1 and 15, then our hypotenuse as 15.
1^2 = 1
15^2 = 225
15^2 = 225
1 + 225 = 226
226 =\ 225.
Your answer is:
No, you cannot construct a triangle with the side lengths of 1, 15 and 15.
I hope this helps!