Math

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AAS Triangle Calculator.

Solve the missing side, angle, area, and perimeter of a triangle from two angles and a non-included side.

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Set your values

Results update as you type.

Result: C = 90.000000° · b = 8.660254 · c = 10.000000 · Area = 21.650635

Result

C = 90.000000° · b = 8.660254 · c = 10.000000 · Area = 21.650635

Use Cases

Geometry homework and exam prep

Quickly verify your manual calculations for AAS triangle problems, ensuring you get the correct side lengths, area, and perimeter.

Example: Given Angle A=40°, Angle B=60°, and side a=10, find the missing values.

Construction and design planning

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

Example: Calculate the length of a roof rafter when you know the pitch angles and one known side.

Frequently Asked Questions

What does AAS mean in triangle calculations?
AAS stands for Angle-Angle-Side. It means you know two angles and a side that is not between them. This calculator uses those inputs to find the remaining side, angle, area, and perimeter.
How do I find the missing angle in an AAS triangle?
The sum of all angles in a triangle is always 180 degrees. So, subtract the two given angles (Angle A and Angle B) from 180 to get the third angle. The calculator does this automatically.
Can I use this calculator if I only know two angles and the side between them?
No, that is an ASA (Angle-Side-Angle) triangle. This calculator is specifically for AAS, where the known side is not between the two given angles. For ASA, you would need a different tool.

Tips & Common Mistakes

Tips

  • Ensure Angle A and Angle B are in degrees, not radians, before entering them.
  • The sum of Angle A and Angle B must be less than 180 degrees for a valid triangle.
  • Side a is the side opposite Angle A. Double-check that you are entering the correct side corresponding to the given angle.
  • Use the calculated area and perimeter to cross-check your own work or to plan material quantities.

Common Mistakes to Avoid

  • Entering angles in radians instead of degrees, leading to incorrect results.
  • Confusing which side is 'a' – it must be opposite Angle A, not just any side.
  • Assuming the given side is between the two angles, which would be an ASA triangle, not AAS.

Last updated: August 13, 2026