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ASA Triangle Calculator.

Solve a triangle from one side and two angles (ASA).

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Set your values

Results update as you type.

Angle C: 75 °

Angle C

75.000000°
Side b: 12.247449 units

Side b

12.247449units
Side c: 13.660254 units

Side c

13.660254units

Results update automatically as you type.

Use Cases

Geometry Homework and Exams

Quickly verify your manual calculations for ASA triangle problems, ensuring accuracy in assignments and test preparation.

Example: Given side c = 10, angle A = 40°, angle B = 60°, find side a and b.

Construction and Design Layouts

Determine unknown dimensions of triangular components when you know one side and two angles, useful for framing, roofing, or land surveying.

Example: Calculate the length of a roof rafter when you know the base and the two base angles.

Frequently Asked Questions

What does the ASA Triangle Calculator do?
It solves a triangle when you know one side and the two angles adjacent to it (ASA). Enter the known side and angles A and B, and it calculates the remaining angle, the other two sides, and the area.
How is the third angle calculated?
The sum of angles in any triangle is always 180°. So, the third angle C is found by subtracting angles A and B from 180°: C = 180° - A - B.
Can I use this calculator for any ASA triangle?
Yes, as long as the two given angles sum to less than 180° and the side is positive. The calculator uses the Law of Sines to find the missing sides, so it works for any valid ASA triangle.

Tips & Common Mistakes

Tips

  • Ensure the sum of angles A and B is less than 180°, otherwise the triangle is invalid.
  • Use consistent units for the known side (e.g., meters, feet) – the calculator will output sides in the same unit.
  • Angles must be entered in degrees, as indicated by the unit field.
  • Double-check your angle values: a small error can significantly affect the computed side lengths.

Common Mistakes to Avoid

  • Entering angles in radians instead of degrees – always use degrees as specified.
  • Forgetting that the sum of all angles must be 180°, so if A + B ≥ 180°, the input is invalid.
  • Confusing which side is opposite which angle – the known side must be opposite the angle you intend to use in the Law of Sines.

Last updated: August 13, 2026