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April 20, 2014

April 20, 2014

Posted by **Anonymous** on Saturday, November 24, 2007 at 4:48pm.

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sin^2x = 1 = cos^2x

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Work:

cos^2x - cos^2x = 0

0 = 0

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Textbook Answers:

90 and 270

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Btw, how would you isolate for cos^2x = 0? Would it be...

x = cos^-1 square root of _____ ?

- Math - Solving Trig Equations -
**Michael**, Saturday, November 24, 2007 at 5:29pmShould this be...

sin^2x - 1 = cos^2x ??

Your equation has two equal signs.

- Math - Solving Trig Equations -
**Anonymous**, Saturday, November 24, 2007 at 5:31pmYeah it should be, sorry for the typo

- Math - Solving Trig Equations -
- Math - Solving Trig Equations -
**Michael**, Saturday, November 24, 2007 at 5:37pmHmm... that's tricky. I solved it one way (similar to your method), and it didn't work. Anyway, this works...

(1) Subtract the cos^2(x) from both sides.

(2) Substitute "1 - sin^2(x)" in for cos^2(x). That comes from the #1 Identity: sin^2(x) + cos^2(x) = 1.

(3) Simplify and factor.

You should get the right answer that way. Let me know if you run into any problems.

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