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July 3, 2015

July 3, 2015

Posted by **Anonymous** on Saturday, November 7, 2009 at 10:19pm.

sinx = (square root of) 1 - cos^2x

is not an identity

- Math -
**Reiny**, Saturday, November 7, 2009 at 10:40pmAll we need is one counterexample to show it is not an identity.

let x = 210º

LS = sin 210 = -1/2

RS = √(1- cos^2 (210º))

= √(.25)

= 1/2

So there!