Triangle Calculator

Calculate the area, perimeter, unknown sides, unknown angles, altitudes, medians, circumradius, and inradius of a triangle given either its three side lengths (side-side-side), two side lengths and the angle between the two sides (side-angle-side), or two angles and the length of the side adjacent to both angles (angle-side-angle). In this calculator, angle A is the angle opposite side A, angle B is the angle opposite side B, and angle C is the angle opposite side C (see the diagram below). When angle units are set to radians, you may enter answers in terms of pi, such as "2/5pi" or "pi/3".

Known values: Side, side, side Side, angle, side Angle, side, angle

Side A:

Side B:

Side C:

Angle units: Radians Degrees
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Glossary of terms

Altitude: (aka height) The shortest distance from a side to the vertex opposite it, or equivalently, the length of a line segment perpendicular to a side that connects that side to the opposite vertex. The area of a triangle is equal to half of any side length multiplied by the corresponding altitude.
Median: The distance from the midpoint of a side to the vertex opposite it.
Circumradius: The radius of the circumscribed circle, the circle drawn around the triangle whose circumference touches all three vertices.
Inradius: The radius of the inscribed circle, the circle drawn within the triangle whose circumference touches all three sides.

Diagram