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Triangle Calculator
Calculate triangle sides, angles, and area
How It Works
Computes the edges, angles, area, height, perimeter, median, inradius, and circumradius of a triangle given any 3 values including at least one side.
A triangle is a polygon with three vertices joined by three edges. Triangles are classified by side lengths: equilateral (all sides equal), isosceles (two sides equal), and scalene (no sides equal). By internal angles: right (one 90° angle), oblique (not right), obtuse (one angle > 90°), and acute (all angles < 90°). Interior angles sum to 180°. The sum of any two sides must be greater than the third side (triangle inequality).
The area can be computed via base×height/2, via two sides and the included angle, or via Heron's formula when all three sides are known. The law of sines relates side lengths to sines of opposite angles. The median extends from a vertex to the midpoint of the opposite side. The inradius is the radius of the largest inscribed circle, and the circumradius is the radius of the circle passing through all three vertices.
Results
Enter values to see results
Quick Tips
- • Results update automatically as you type
- • Use Tab to navigate between fields
- • Press Enter to calculate