What Types of Triangles There Are

A triangle is a polygon that has 3 angles, and 3 line segments joined end to end. Thus, we can say that a triangle is a polygon, which has 3 sides, 3 angles, 3 vertices, and the sum of all 3 angles of any triangle equals 180°. Sides and angles define the type of triangle.

5-Minute Crafts would like to tell you about what types of triangles there are. In the bonus section, we’ll recall some terms from our school geometry course.

Types of triangles by angle

• A right triangle has one angle equal to 90°.
• An acute triangle has 3 angles that are all less than 90°.
• An obtuse triangle has one angle that is more than 90°.

Types of triangles by side

• All 3 sides of an equilateral triangle are equal. Since all 3 sides have the same length, all 3 angles are equal too. Each angle of an equilateral triangle is 60°.
• 2 sides out of 3 on an isosceles triangle have the same length.
• All 3 sides of a scalene triangle have different lengths.

Bonus: Terms that describe the elements of an triangle

• The legs are the sides in a right triangle that form its right angle (90°).
• The hypotenuse of a right triangle is the side opposite its right angle.
• The median of a triangle is a line segment that joins one of its vertices with the center of the opposite side.
• The altitude of a triangle, or height, is a line from a vertex to the opposite side, that is perpendicular to that side.
• An angle bisector of an angle of a triangle divides the opposite side into 2 segments that are proportional to the other 2 sides of the triangle.