Law of Sines Calculator

The Law of Sines Calculator substitutes your inputs (Side a, Angle A (°), Angle B (°)) into the standard expression: Side b = Side a × sin(Angle B (°) × π ÷ 180) ÷ sin(Angle A (°) × π ÷ 180). Every variable is read straight from the fields on this page, and the result is computed the moment you enter the values.

1. 1

   Step 1

   Type the required numbers in the input fields.

2. 2

   Step 2

   Click the "Calculate" button to see the result instantly.

3. 3

   Step 3

   You can re-run the calculation with different values anytime.

4. 4

   Step 4

   The breakdown lists your inputs — Side a, Angle A (°) next to the value computed by Side b = Side a × sin(Angle B (°) × π ÷ 180) ÷ sin(Angle A (°) × π ÷ 180); read it before relying on the number.

5. 5

   Step 5

   Adjust one input at a time and compare scenarios: change Side a and re-run to see which variable moves the law of sines result most.

• 1

  The Law of Sines Calculator needs every variable in consistent units — Side a, Angle A (°) — before the standard formula returns a valid result, so check each field's unit before entering values copied from elsewhere.

• 2

  Enter values in the units the Law of Sines fields expect — Side a, Angle A (°) and the rest; mismatched units are the most common way a correct formula yields a wrong number no calculator can detect.

• 3

  Round only at the end: Law of Sines carries full precision internally, so rounding intermediate values by hand can shift the final answer more than the accuracy of the formula itself ever would.

• Zero and negatives can sit outside the formula's domain: zero angle a (°) may make the Law of Sines undefined, and a negative side a still returns a number. Check each input is inside the range the quantity allows.

• Swapping Side a with Angle A (°) computes a different quantity. If the Law of Sines result looks implausible, check the labels first: each value must sit in the field its label names.