If it has one right angle (90 degrees), it is a right triangle. If it has one obtuse angle (more than 90 degrees), it is an obtuse triangle. If it has more than one acute angle (less than 90 degrees), it is an acute triangle.
the answer is 90 degrees A right angle measures 90 degrees. More than 90 degrees is an obtuse angle and less than 90 degrees is an acute angle. Any triangle with an angle that measures 90 degrees is known as a right triangle.
A triangle has 180 degrees. A right triangle has exactly one angle measuring 90 degrees. If you know that one of the other angles of the triangle is 20 then your third angle is: 180-90-20 = 70 degrees.