Question

The sides of a triangle have length 11, 15 and k, where k is an integer. Then the number of values of k for which the triangle is obtuse is

(A)  5 

(B)  12 

(C)  13

(D)  17

Answer 1

Correct option (C) 13

4 < k < 26

For triangle to be obtuse

Either 11² + 15² < k²

or  11² + k²< 15²

⇒ k ∈ {5, 6, 7, 8, 9, 10, 19, 20, 21, 22, 23, 24, 25}