Math - Solving Trig Equations

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Solve each equation for o is less than and/or equal to theta is less than and/or equal to 360


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

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 -

    Should this be...

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

    Your equation has two equal signs.

  • Math - Solving Trig Equations -

    Yeah it should be, sorry for the typo

  • Math - Solving Trig Equations -

    Hmm... 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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