Question

Tell if the measures 9, 11, and 7 can be side lengths of a triangle. If so, classify the triangle as acute, right, or obtuse.

Answer 1

If A, B, and C are sides of an arbitrary triangle, then no two sides may sum to be larger than the length of the third side.
A + B < C
A + C < B
B + C < A
Those three things must all be true.

Answer 2

Here's why.

If C is larger than A + B, then I can't open the angle between A and B wide enough to make the ends meet =(

Answer 3

That makes so much sense, thanks.

Answer 4

=D My pleasure!