The Triangle Calculator helps when you know part of a triangle and want the rest filled in without switching between several geometry formulas. Enter three sides (SSS), two sides with their included angle (SAS), one side with two angles (ASA/AAS), or supported right-triangle data. The page detects the entered combination and fills in missing sides and angles when the information is sufficient.
The output is more than one missing value. For a solvable triangle, it also reports area, perimeter, semiperimeter, all three heights, all three medians, inradius, circumradius, angle values in radians, a type label, and a visual triangle diagram. It is useful for geometry homework, dimension checks, layout estimates, and understanding how Heron's formula, the law of sines, and the law of cosines fit together.
If you only need a right-triangle hypotenuse or leg, use the Pythagorean Theorem Calculator. For a general equation or numeric expression, use the Equation Solver or Mathematical Expression Calculator.
This is not an SSA ambiguous-case solver, and three angles alone do not determine a triangle's scale. A side is still required to determine absolute lengths.
Side values must be positive; leave unknown sides blank. When all three sides are supplied, the page uses the law of cosines for the interior angles and Heron's formula for the area. The three sides must also satisfy the triangle inequality: every pair must add to more than the remaining side.
You need at least three valid numeric values and at least one side; the page supports three sides, two sides with their included angle, one side with two angles, and supported right-triangle combinations.
No. The current page treats two sides plus their included angle as SAS and is not an SSA ambiguous-case solver.
Enter angles in degrees, such as 30, 45, or 90; the result also reports the corresponding radian values.
All sides must be positive and the sum of any two sides must be greater than the third; equality describes a degenerate line, not a valid triangle.
The page has no unit selector. Perimeter, heights, and radii follow the side unit, while area uses the squared side unit.
Supports SSS, SAS, ASA/AAS, and right-triangle data to fill missing sides and angles and calculate area, perimeter, heights, medians, and circle radii.