Question

Find an integer, x, such that 2, 4, and x represent the lengths of the sides of an obtuse triangle.

Answer 1

a^2 + b^2 < c^2 for the triangle to be obtuse
2^2 + 4^2 < x^2
4 + 16 < x^2
20 < x^2
sqrt 20 = 4.7 approx 5
x needs to be greater than or equal to 5 for the triangle to be obtuse.
4 + 16 < 25
20 < 25