Question

Determine if a triangle with side lengths 7, 9, and 12 is acute, right, or obtuse.

Answer 1

Answer:

  Obtuse

Step-by-step explanation:

The sum of squares of the short sides is 130, so is less than the square of the long side. The long side (12) is longer than it would need to be for a right triangle, so the largest angle is bigger than 90°.

The triangle is obtuse.

_____

A triangle solver app or calculator can confirm this. Note angle C is about 96°, an obtuse angle.