Right Triangle Calculator
Solve all three sides from one acute angle and one known side, with area and complementary angle checks.
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Solve a right triangle from an angle and one side
Enter an acute angle, choose whether the known length is the hypotenuse, adjacent side or opposite side, and provide that length. The calculator applies sine, cosine and tangent relationships to recover all three sides, then reports area and the complementary acute angle. This extends beyond a two-leg Pythagorean check by supporting the common angle-plus-side problem.
Confirm the diagram and units before using the result
Adjacent and opposite are defined relative to the entered angle, and the model assumes an exact ninety-degree corner. All side outputs use the same unit as the known length. Measurement tolerances, rounded angles and non-right geometry can change a layout, so verify the reference angle and preserve precision appropriate to the source measurements.
Frequently asked questions
How are adjacent and opposite defined?
They are named relative to the acute angle entered by the user.
Can the entered angle equal 90 degrees?
No. It must be greater than zero and less than ninety degrees.
Which unit does the result use?
Every side uses the same length unit as the known side.