Brian Monetti, I <3 math!
All triangles on a 2 dimensional plane will have at least 2 acute angles. This is because the sum of the three angles will always be 180 degrees. Two of the three numbers which add up to make 180 must be less than 90. If two of the numbers were equal to or greater than 90, then it would not make a triangle because it would add up to over 180.
On three dimensional figures it is possible to create triangles which have more than 180 degrees, but this goes into the realm of non-Euclidean, which is a very specialized field of geometry. One example of a triangle like this would be on one drawn on a sphere, where you can draw a triangle with only straight lines and have each angle be 90 degrees! A triangle made from the north pole down to the equator, then 90 degrees along the equator, then back to the north pole, will have the sum of the angles equal to 270 degrees!