We take 3 points and connect them with 3 sides below denoted as ΔPQR:

Properties of a Triangle:

Sum of the three interior angles = 180° Sum of the 2 sides > 3rd side A triangle with vertices (points) P, Q, R: is denoted as ΔPQR

Area of a Triangle

With base b and height h: A = 1/2bh

Acute Triangle:

All 3 angles measure less than 90°

Right Triangle:

Has one angle measuring 90° (right) The other two angles < 90°

Obtuse Triangle:

Has only one angle measuring > 90° Obtuse angle is opposite the long side

Scalene Triangle

No Sides Are Equal

Isosceles Triangle

2 sides Are Equal

Equilateral Triangle

All 3 sides are equal

How does the Triangles Calculator work?

Free Triangles Calculator - This lesson walks you through the basics of a triangle and shows you triangle types like acute, right, obtuse, scalene, isosceles, equilateral.

What 2 formulas are used for the Triangles Calculator?

Triangle PQR is written as ΔPQR The sum of the three interior angles of a triangle equals 180°