Triangle Calculator: Fast and Friendly Math Help

This triangle calculator finds every side and angle from what you know. Enter a few values and get area, perimeter, and a clean sketch. Use it for class, site checks, or quick planning.

What Is a Triangle Calculator?

A triangle calculator uses the law of sines and the law of cosines. It fills in missing sides and angles from valid inputs. The tool supports five input methods. SSS means three sides. SAS means two sides and the angle between them. ASA means two angles and the side between them. AAS means two angles and a side opposite one angle. SSA means two sides and the angle opposite one side. Angles use degrees.

Results include full triangle geometry. You see sides, angles, area, perimeter, semiperimeter, and a scaled diagram. Sides show three decimal places. Angles show two. Area and perimeter show three. The semiperimeter shows three as well. Your length unit carries through to area in square units.

How to Use the Tool

1. Choose a method from the list.
2. Enter the inputs that appear.
3. Use degrees for all angles.
4. Enter positive lengths.
5. Click Calculate to view results.
6. Click Reset to clear all fields.

By convention, side a sits opposite angle A. Side b sits opposite angle B. Side c sits opposite angle C.

Input guide by method

• SSS three sides
  • Enter side a and side b and side c.
  • Use positive lengths for each side.
  • Any two sides add to more than the third.
• SAS two sides and included angle
  • Enter side a and angle C and side b.
  • Angle C sits between sides a and b.
  • Angle C lies between 0 and 180 degrees.
• ASA two angles and included side
  • Enter angle A and side c and angle B.
  • Side c sits between angles A and B.
  • Angles A and B add to less than 180 degrees.
• AAS two angles and a non included side
  • Enter angle A and angle B and side a.
  • Side a sits opposite angle A.
  li>Angles A and B add to less than 180 degrees.
• SSA two sides and a non included angle
  • Enter side a and side b and angle A.
  • Angle A sits opposite side a.
  • This case can produce two triangles.

What the results mean

• Sides a and b and c are the three edge lengths.
• Angles A and B and C are the three corner angles in degrees.
• Area is the space inside the triangle in square units.
• Perimeter is the total length around the triangle.
• Semiperimeter equals half the perimeter.
• Diagram shows a scaled sketch with labels for sides and angles.

How the math works

• The law of cosines finds sides or angles from mixed inputs.
• The law of sines links side ratios to angle sines.
• Area uses Heron's formula after all sides are known.

Notes and limits

• Use one length unit across all sides.
• Angles use degrees only.
• SSA can allow two shapes for one set of values.
• The calculator returns one valid triangle when possible.
• Rounding can create tiny gaps in angle sums.
• The diagram scales to fit and shows labels for quick checks.

Benefits You Will Enjoy

This triangle calculator saves time and gives clear steps. You get consistent results without manual algebra. It works well for quick checks and study sessions.

Common use cases

• Solve a homework set from three sides with SSS.
• Find a missing side from two sides and an angle with SAS.
• Complete a design where two angles and a side are known with ASA.
• Estimate area for a plot from two angles and one side with AAS.
• Check survey notes from two sides and an opposite angle with SSA.

Enter your known values and let the triangle calculator do the heavy lifting. Accurate inputs lead to reliable sides, angles, and area. Keep units consistent and you get clean, ready to use results.