Triangle Calculator

Solve any triangle from 3 known values. Compute all sides, angles, area, perimeter, and draw diagrams.

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1. Enter any three known values from the six triangle properties (three sides and three angles). 2. The calculator detects the case type (SSS, SAS, ASA, AAS, or SSA) automatically. 3. View all missing sides, angles, area, and perimeter computed instantly. 4. For the ambiguous SSA case, both possible triangle solutions are shown. 5. Review the visual triangle diagram that updates with your values. 6. Click the copy button to copy any calculated value.

About This Tool

The Triangle Calculator is a comprehensive geometry tool that solves any triangle when you provide at least three known values - any combination of sides and angles. Whether you have three sides (SSS), two sides and an included angle (SAS), two angles and a side (AAS or ASA), or two sides and a non-included angle (SSA), this calculator finds all missing measurements including the remaining sides, angles, area, and perimeter.

Under the hood, the tool applies the Law of Cosines and Law of Sines to resolve unknown values step by step. It also detects ambiguous cases in SSA configurations where two valid triangles may exist, presenting both solutions so you never miss a possibility. The area is computed using the cross-product formula (0.5 * a * b * sin C), and results are displayed with adjustable decimal precision.

Beyond raw numbers, the calculator renders a scaled diagram of your triangle with labeled sides and angles, making it easy to visualize the solution. This is invaluable for students working through trigonometry homework, engineers verifying structural dimensions, or anyone who needs quick and accurate triangle measurements without manual computation.

Formula / How It Works

Law of Cosines: c^2 = a^2 + b^2 - 2ab*cos(C) | Law of Sines: a/sin(A) = b/sin(B) = c/sin(C) | Area = 0.5*a*b*sin(C)

Frequently Asked Questions

You can enter any three known values that define a triangle: three sides (SSS), two sides and the included angle (SAS), two angles and one side (AAS or ASA), or two sides and a non-included angle (SSA). The calculator automatically detects the case and solves accordingly.
The ambiguous case occurs with SSA (two sides and a non-included angle). Depending on the values, there may be zero, one, or two valid triangles. The calculator checks all possibilities and displays every valid solution.
The area is calculated using the formula Area = 0.5 * a * b * sin(C), where a and b are two sides and C is the angle between them. For SSS cases, the tool first finds an angle using the Law of Cosines, then applies this formula.
Yes. After solving, a scaled diagram is drawn with all sides and angles labeled. The diagram adjusts to the proportions of your specific triangle so you can visually verify the result.
Absolutely. Right triangles are a special case where one angle is 90 degrees. You can enter 90 as one angle along with two other known values. For dedicated right-triangle work, check out the Pythagorean Theorem Calculator as well.

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