To test for the type of triangle:
1) Square all 3 sides.
2) Sum the squares of the 2 shortest sides.
3) Compare this sum to the square of the 3rd side.
if sum > 3rd side² Acute Triangle
if sum = 3rd side² Right Triangle
if sum < 3rd side² Obtuse Triangle
1) 49
121
144
2)
49 + 121 = 170
3) 170 < 144
Therefore, it is an obtuse triangle.
Source
1728.com/triantest.htm
