SOLUTION: The sides of a triangle have lengths 6, 14, and 18. What kind of triangle is it?

If a, b and c are the lengths of the sides of a triangle, and "c" is the longest 
side, then


    a) the triangle is a right angled triangle if   +  = ;


    b) the triangle is an acute triangle if  +  > ;


    c) the triangle is an obtuse triangle if  +  < .


Having this instruction, check it on your own, that in you case you have an obtuse triangle.