Acute angle
An angle whose measure is greater than 0 but less than 90 degrees.

Acute triangle
A triangle whose angles are acute.

CPCTC

Corresponding Parts of Congruent Triangles are Congruent.

Equilateral triangle
A triangle whose sides are equal in length.

Isosceles triangle
A triangle with two sides of equal length.

Obtuse angle
An angle whose measure is greater than 90 but less than 180 degrees.

Obtuse triangle
A triangle with one acute angle.

Right triangle
A triangle that has a 90 degree angle.

Scalene triangle
A triangle with no equilateral sides.

Triangle
A polygon with three sides.