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 mathkid February 24th, 2013 07:37 PM

trick question

_____ -8sin^2(x) = 8cos^2(x)

:mrgreen:

 MarkFL February 24th, 2013 07:40 PM

Re: trick question

Hint: $1-\sin^2(x)=\cos^2(x)$

Now multiply through by 8.

 soroban February 24th, 2013 08:04 PM

Re: trick question

Hello, mathkid!

A strange way to write the problem . . .

Quote:
 $\text{Fill in the blank: }\;\_\!\_\!\_\!\_\,-\,8\sin^2x \:=\:8\cos^2x$

$\text{W\!e have: }\:Z \,-\,8\sin^2x \:=\:8\cos^2x$

[color=beige]. . . . . . . . . . . . . . . [/color]$Z \:=\:8\sin^2x\,+\,8\cos^2x$

[color=beige]. . . . . . . . . . . . . . . [/color]$Z \:=\:8\,\underbrace{(\sin^2x\,+\,\cos^2x)}_{\text{ This is 1}}$

[color=beige]. . . . . . . . . . . . . . . [/color]$Z \:=\:8$

 mathkid February 25th, 2013 03:51 AM

Re: trick question

ok yes I know the sin squared + cos squared = 1 solving algebraically for the missing variable or blank was so simple seeing it now. I just need to practice the trig more. makes me want to puke sometimes...lol

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