Triangle Calculator with Steps
Solve any triangle instantly. Find missing sides, angles, area, and perimeter with detailed step-by-step explanations.
Sides (Lengths)
Angles (Degrees)
Why Use Our Triangle Calculator?
Solves Any Triangle
Whether it's a right triangle or an oblique one, our calculator handles SSS, SAS, ASA, and AAS cases.
Step-by-Step
Don't just get the answer. See exactly how it was calculated using the Law of Sines and Law of Cosines.
Homework Helper
Perfect for checking your geometry homework and understanding the trigonometry behind the solution.
How to Solve Triangles
Solving a triangle means finding the lengths of all three sides and the measures of all three angles. To do this, you need to know at least three values, and at least one of them must be a side.
Key Formulas
- Law of Sines: Useful when you know a side and its opposite angle.
- Law of Cosines: Useful when you know two sides and the included angle (SAS) or all three sides (SSS).
- Angle Sum Property: The sum of angles in a triangle is always 180°.
Frequently Asked Questions
What is the Law of Sines?
The Law of Sines states that the ratio of the length of a side of a triangle to the sine of the angle opposite that side is the same for all sides and angles in a given triangle: a/sin(A) = b/sin(B) = c/sin(C).
What is the Law of Cosines?
The Law of Cosines relates the lengths of the sides of a triangle to the cosine of one of its angles. It generalizes the Pythagorean theorem: c² = a² + b² - 2ab*cos(C).
How many values do I need to solve a triangle?
You need at least 3 known values, and at least one of them must be a side length. Knowing only 3 angles is not enough because the triangle could be any size (similar triangles).