Question 146185
1. All sides are equal, thus by theorem all angles are equal. So 3s=180, s=60. This is acute.

2. Look at the Pythagorean Theorem. a^2+b^2=c^2. Do these sides fit? 3^2+4^2=9+16=25.. sqrt(25)=5, yes. Thus it must be a right triangle.

3. The inequality relation {{{a^2+b^2<c^2}}} must be met if this is an obtuse triangle.

5^2+11^2=25+121=136<144. Thus it must be an obtuse triangle.