#5 is not an isosceles or equilateral because all the side measurements are different. So it is a scalene, and it has an angle that is more than 90 which also makes it obtuse. #6 is also scalene, but because all the angle measurements are smaller than 90, it is acute.
#5). In a triangle, the angles track the sides in some interesting ways.
-- If all of the sides are the same length, then the angles are all the same size.
-- If two sides are the same length, then two of the angles are the same size.
-- If the sides are all different lengths, then all of the angles are different sizes.
#5). All of the sides are different lengths. That's called a "scalene" triangle. (You're supposed to know that by now.)
One of the angles is more than 90 degrees. That's called an "obtuse" angle. If a triangle has an obtuse angle in it, it can't have more than one of them, and it's called an "obtuse triangle".
#6). All of the sides are different lengths. That's called a "scalene" triangle. (You're supposed to know that by now.)
All of the angles are less than 90 degrees. Those are called "acute angles". A triangle with three acute angles is called an "acute triangle".