Question

9. If two sides in one triangle are 9 and 21 , then the third side might be

a) 9
b) 11
c) 12
d) 13

Please explain how you got the answer ​

Answer 1

d

Explanation:

given 2 sides of a triangle then the third side x is in the range

difference of 2 sides < x < sum of 2 sides , that is

21 - 9 < x < 21 + 9 , so

12 < x < 30

the only value that satisfies the inequality is 13