Answer:
Triangle number one is a right triangle. Triangle two is an equilateral triangle. Triangle three which is below triangle one is an obtuse triangle. The fourth triangle is an acute triangle.
Explanation:
One is a right triangle because it has one right angle.
Two is an equilateral triangle because all of the three angles are 60 degrees.
Three is an obtuse triangle because one of the three angles is more than 90 degrees.
Finally, 4 is an acute triangle because all of the three angles are less than 90 degrees