Can the law of cosines calculator find angles if I only know the three side lengths?

2-3 sentence answer grounded in the material

Do these calculators work for right triangles too?

1-3 sentence answer grounded in the material

What units should I use for the angle input?

1-3 sentence answer grounded in the material

Is the result from these calculators precise enough for engineering calculations?

1-3 sentence answer grounded in the material

Trigonometry3 options compared

Law of Cosines Calculator

Calculates unknown sides and angles within a non-right triangle using the Law of Cosines formula. Users input specific measurements to determine missing values, offering two primary functions. The first function allows users to find the length of the third side when given two known sides and the included angle (SAS). Alternatively, it can calculate the internal angles of a triangle when all three...

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Editors’ Top PickBased on community votes

Omni Calculator

omnicalculator.com

Use this law of cosines calculator to determine the third side of a triangle knowing two sides and the angle between ...

Open Omni Calculator Read review →

Other OptionsRanked by votes

02
02
Pi Day Calculators
piday.org
Solves triangle problems using the law of cosines when two sides and an included angle are known.
Open site View details
03
03
X10Tools
x10tools.com
Calculate a triangle’s third side from two sides and the included angle.
Open site View details

Side by side

Law of Cosines Calculator options compared

Tool	Best for	Strengths	Limitations
Omni Calculator omnicalculator.com	Students needing formula context	Community votes for reliability Explains law of cosines formula and applications	May have ads on the page
Pi Day Calculators piday.org	Engineers needing precise unit options	Wide range of angle units (degrees, radians, gradians, etc.) Accepts side measurements in multiple units (mm, cm, inches, etc.)	No community votes or user feedback available
X10Tools x10tools.com	Quick one-off calculations without account	No account required Instant results, easy to copy	Fewer unit options for sides and angles Ads present on the page

Buyer's guide

How to choose a law of cosines calculator

When picking a law of cosines calculator, first decide whether you need to find a missing side (SAS) or missing angles (SSS) — most tools handle both but some emphasize one function. Check the unit support if your measurements use non-standard units like yards or milliradians, and look for community votes or user reviews to assess reliability for important work.

Questions

Law of Cosines Calculator FAQ

Can the law of cosines calculator find angles if I only know the three side lengths?: 2-3 sentence answer grounded in the material
Do these calculators work for right triangles too?: 1-3 sentence answer grounded in the material
What units should I use for the angle input?: 1-3 sentence answer grounded in the material
Is the result from these calculators precise enough for engineering calculations?: 1-3 sentence answer grounded in the material

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