Given that a is the longest side length in the triangle, which of the following inequalities would make the triangle above an obtuse triangle?
a. a2+b2< c2 b. a2+b2> c2 c. b2+c2< a2 d. b2+c2> c2

The equations presented in the choices above are all derived from the Pythagorean theorem. This states that the sum of the squares of the two shorter sides is equal to the square of the longest side which is also referred to as the hypotenuse. 

If the sum of the squares of the shorter sides is smaller compared to the square of the hypotenuse then, the triangle is OBTUSE. The answer therefore to this item is letter A.