Complex sentence: An acute triangle is a triangle with all three of its angles being acute (less than 90 °), while an obtuse triangle is one that has one obtuse angle (greater than 90 °) and two acute angles.
Split into simpler sentences: An acute triangle is a triangle with all three angles acute (less than 90 °). An obtuse triangle is one with one obtuse angle (greater than 90 °) and two acute angles.