Is it possible to build a triangle with lengths 8 7 and 15?

No, it is not possible to build a triangle with side lengths of 8, 7, and 15. According to the triangle inequality theorem, the sum of the lengths of any two sides must be greater than the length of the third side. In this case, 8 + 7 equals 15, which is not greater than 15, so these lengths cannot form a triangle.