A right triangle has one 90 degree angle and two acute angles. A special case is an isosceles right triangle that has two equal side lengths, where one angle is equal to 90 degrees and the two acute angles are each equal to 45 degrees.
However, in an acute triangle, all three angles are acute or less than 90 degrees. An equilateral triangle, which has three angles that are each equal to 60 degrees, is an example of an acute triangle.
It also is important to remember that for any triangle, the sum of all three angles has to equal 180 degrees. Likewise, there can be other triangles, such as an obtuse triangle (one of the three angles is greater than 90 degrees) that can also have acute angles at the same time.Learn more about Geometry