Law of cosines
Law of cosines: use side a, side b, included angle. Review the formula, worked example and calculation steps.
Inputs
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Formula & explanation
c = √(a²+b²−2ab cos C)
Variables & units
- Side a
- m · minimum 0.000001, maximum 1000000000000
- Side b
- m · minimum 0.000001, maximum 1000000000000
- Included angle
- ° · minimum 0.000001, maximum 179.999999
Worked example
Sides 3 and 4 with a 90° included angle give side 5.
Assumptions
The angle is between the two known sides.
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Practice with an example
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