When given 3 triangle sides, to determine if the triangle is acute, right or obtuse:
1) Square all 3 sides.
4, 3, 4,
16, 9, 16
2) Sum the squares of the 2 shortest sides.
16 + 9 = 25
3) Compare this sum to the square of the 3rd side.
25 > 16
if sum > 3rd side² Acute Triangle
So, it is an acute triangle.
Source:
http://www.1728.org/triantest.htm
