» Triangle Calculator

What does this triangle calculator solve?
This triangle calculator solves missing triangle values from common combinations of three known inputs. It can calculate sides, angles, perimeter, area, heights, medians, inradius, and circumradius.

Can I use it as a triangle sides calculator?
Yes. If your known values are enough to define a valid triangle, the calculator can solve the missing side lengths. Common cases include three sides, two sides and one angle, or one side and two angles.

Can I use it as a triangle angle calculator?
Yes. The calculator can find missing triangle angles when the given sides or side-angle combination determines a unique triangle. For example, if you know all three sides, it calculates the three interior angles automatically.

How do I calculate the perimeter of a triangle?
Add the three side lengths: P = a + b + c. This page works as a triangle perimeter calculator because it first solves any missing side lengths and then adds them to get the perimeter.

How do I solve a triangle from sides and angles?
Enter any valid set of three known values. The calculator supports side-side-side, side-side-angle, side-angle-angle, and other standard cases. Once the known values define a valid triangle, it computes the remaining sides, angles, and derived measures.

Why does a triangle sometimes have two solutions or no solution?
In the side-side-angle case, the known values can produce two possible triangles, one triangle, or no triangle. The calculator shows the two-solution choice when that ambiguous case occurs and shows an alert when the given measurements do not form a valid triangle.