Cal11 calculator

Triangle Calculator Degrees Sss

Reviewed by Calculator Editorial Team

This triangle calculator solves for all angles and sides of a triangle when three sides are known (SSS method) using degrees. It uses the Law of Cosines to determine the angles and then applies the Law of Sines to find the remaining sides.

What is the SSS Triangle Method?

The SSS (Side-Side-Side) method is a way to solve for all angles and sides of a triangle when you know the lengths of all three sides. This is one of the three main methods for solving triangles (along with SAS and ASA).

To solve a triangle using the SSS method:

  1. First, use the Law of Cosines to find one of the angles
  2. Then use the Law of Sines to find another angle
  3. The third angle can be found by subtracting the other two angles from 180°
  4. Finally, use the Law of Sines again to find the remaining side

Note: The SSS method only works when the sum of any two sides is greater than the third side (triangle inequality theorem).

How to Use This Calculator

  1. Enter the lengths of all three sides of your triangle in the input fields
  2. Click the "Calculate" button
  3. View the results including all angles and sides
  4. Use the chart to visualize the triangle

The calculator will automatically check if the triangle is valid according to the triangle inequality theorem before performing calculations.

Formula and Calculation

The calculator uses these formulas:

Law of Cosines: c² = a² + b² - 2ab cos(C)

Law of Sines: a/sin(A) = b/sin(B) = c/sin(C)

Where:

  • a, b, c are the lengths of the sides
  • A, B, C are the angles opposite to sides a, b, c respectively

The calculation process is:

  1. Calculate angle C using the Law of Cosines
  2. Calculate angle B using the Law of Sines
  3. Calculate angle A as 180° - A - B
  4. Calculate side c using the Law of Sines

Worked Example

Let's solve a triangle with sides a=5, b=6, c=7:

  1. Calculate angle C:
    cos(C) = (5² + 6² - 7²)/(2×5×6) = (25+36-49)/60 = 12/60 = 0.2 C = arccos(0.2) ≈ 78.46°
  2. Calculate angle B:
    sin(B) = (b×sin(C))/c = (6×sin(78.46°))/7 ≈ (6×0.9781)/7 ≈ 0.8396 B ≈ arcsin(0.8396) ≈ 57.22°
  3. Calculate angle A:
    A = 180° - 78.46° - 57.22° ≈ 44.32°
  4. Calculate side c (already given as 7 in this example)

This example shows how the calculator arrives at the solution for any valid triangle.

Frequently Asked Questions

What is the SSS method in triangles?

The SSS method is a way to solve for all angles and sides of a triangle when you know the lengths of all three sides. It uses the Law of Cosines and Law of Sines to find the unknown values.

How do I know if a triangle is solvable with the SSS method?

A triangle is solvable with the SSS method if the sum of any two sides is greater than the third side (triangle inequality theorem). The calculator checks this automatically.

What happens if I enter sides that don't form a valid triangle?

The calculator will display an error message explaining that the sides do not form a valid triangle according to the triangle inequality theorem.

Can this calculator handle triangles with angles greater than 90°?

Yes, the calculator can handle all types of triangles including obtuse triangles where one angle is greater than 90°.