The law of sines is a mathematical formula. I have seen it written as both Law of Sines and law of sines. Which one of these is correct?

Edit: According to Google Ngrams, the lower case option was preferred historically, but the title case version has gained in popularity in the past couple of decades.

  • 1
    Nice job with using the NGRAM as a source. Welcome to ELU – David M Mar 18 '14 at 16:48

Wolfram Mathworld is a good source for what is acceptable. They use all lower case in the body of their text.

But if you are submitting an article or paper, you should ask the editors what their standards are.

At Massachusetts Institute of Technology, the guide to capitalization says:

Do not capitalize physical laws, theorems, principles, or constants except for attached proper names:

special theory of relativity

Boyle's law

the third law of thermodynamics

Avogadro's number

Walden University says the same.

As David M notes in the comments here, titles have their capitalization rules, too, which are given in the MIT reference under item 3

| improve this answer | |
  • You've convinced me. Plus one. – David M Mar 18 '14 at 16:33
  • Of note, it would be capitalized when being used as a title. – David M Mar 18 '14 at 16:37
  • I can't believe I type some of these words. Autocorrect MAYHEM! – Canis Lupus Mar 18 '14 at 16:45
  • Thank you, this is exactly what I was looking for. I'll accept it in a bit unless a better answer is given. – Mangara Mar 18 '14 at 16:49
  • Chicago Manual of Style, 15th Edition (at 8.157), says very nearly the same thing as MIT's guide, even down to the examples: "Laws and theories. Names of laws, theories, and the like are lowercased, except for proper names attached to them. [Examples:] Avogadro's hypothesis, the big bang theory, Boyle's law, (Einstein's) general theory of relativity, Newton's first law." Ultimately, it's a house style decision (if there's a house to answer to). – Sven Yargs Mar 18 '14 at 17:06

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