What is the difference between identities and equations

Identities are only useful if you know them, since only then will you recognize that a replacement is possible. But there are a lot of them see trig identities below. Get a feel for the common ones and have a quick reference handy to look them up.

There are dozens of identities in the field of trigonometry. For example, a popular one is: which is one of the so-called double angle identities. Difference between equations, equalities and identities. Share More sharing options Followers 0. Recommended Posts. Posted November 12, The equations above are examples of an equality: a proposition which states that two constants are equal. Many authors reserve the term equation for an equality which is not an identity.

Link to comment Share on other sites More sharing options Posted November 13, Thanks tree, so identities and equalities are just special types of equations right? EuYu Add a comment.

Active Oldest Votes. Lucian Lucian Maybe that's poor form on the part of textbook authors though. Of course, this is going by the language in a precalc book.

Either way, equations and identities assert equality, only identities assert that both sides represent the same mathematical object, which implies that for every valuable of the variable on both sides the equality holds. By all variables, I meant all variables within a certain specified domain. Show 1 more comment. That would be closer. Although equations and identities can both have several variables, and equations can have several solutions.

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