An acute triangle has all angles measuring less than 90º.
Note: It is possible for an acute triangle to also be scalene, isosceles, or equilateral.


A right triangle has one right angle.
(A right angle measures exactly 90º.)
A "box" is used to indicate the location of the right angle.
The longest side of the right triangle (across from the "box") is called the "hypotenuse".
The remaining two sides are referred to as "legs", which may, or may not, be of equal length.
Note: It is possible for a right triangle to also be scalene or isosceles.


An obtuse triangle has one angle measuring more than 90º but less than 180º (an obtuse angle).
It is not possible to draw a triangle with more than one obtuse angle.
Note: It is possible for an obtuse triangle to also be scalene or isosceles. 

An equiangular triangle has three congruent angles.
Each angle has a measure of 60º.
Note: All equiangular triangles are also equilateral.


An oblique triangle is any triangle that is not a right triangle.
It may be acute, obtuse, equiangular, scalene, isosceles, or equilateral, but not a right triangle.

Oblique triangle
= NOT a RIGHT
TRIANGLE 
