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Mathematics 15 Online
OpenStudy (anonymous):

Find x. A. 4 B. 4 times the square root of 2 C. 8 D. 4 times the square root of 3

OpenStudy (anonymous):

OpenStudy (jhannybean):

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OpenStudy (anonymous):

SOH CAH TOA?

OpenStudy (jhannybean):

\[\large \sin(\theta) =\cfrac{opp}{hyp}\]\[\large \tan(\theta) = \cfrac{opp}{adj}\]\[\large \cos(\theta) = \cfrac{adj}{hyp}\]Which one can you apply here?

OpenStudy (anonymous):

one with a hyp

OpenStudy (anonymous):

maybe sin or cos

OpenStudy (jhannybean):

Good, that eliminates \(\tan (\theta)\)

OpenStudy (jhannybean):

Would it be \(\sin(45)=\cfrac{opp}{hyp}\) or \(\cos(45) = \cfrac{adj}{hyp}\)?

OpenStudy (anonymous):

hmmmm i think cos

OpenStudy (jhannybean):

Good :)

OpenStudy (jhannybean):

what can we plug in for the \(\cfrac{adj}{hyp}\)?

OpenStudy (anonymous):

x/18= 45

OpenStudy (jhannybean):

Correction: \[\large \cos(45) = \cfrac{x}{18}\] don't forget the trig part!

OpenStudy (jhannybean):

We can also rewrite it like \(\cfrac{\cos(45)}{1}= \cfrac{x}{18}\)

OpenStudy (jhannybean):

Now how would we solve for x?

OpenStudy (anonymous):

cos(45)*18= x

OpenStudy (anonymous):

right?

OpenStudy (jhannybean):

Great! you got this :D

OpenStudy (anonymous):

9.45?

OpenStudy (jhannybean):

Well, not exactly..

OpenStudy (jhannybean):

Do you know what cos(45) =?

OpenStudy (anonymous):

.707

OpenStudy (jhannybean):

Yes, and that is equivalent to \(\cfrac{\sqrt{2}}{2}\)

OpenStudy (anonymous):

would i then equal one or srt2

OpenStudy (jhannybean):

Hmm.. one minute. I am not getting any of those answers after i simplified this.

OpenStudy (anonymous):

I'm probably wrong I'm not good at simplifying

OpenStudy (bahrom7893):

Any ideas on where you might have gone wrong? Don't feel like scrolling around through the whole thing checking.

OpenStudy (bahrom7893):

We're looking for x, no?

OpenStudy (anonymous):

ya

OpenStudy (anonymous):

that was a ya to were looking for x not for the scrolling around part

OpenStudy (jhannybean):

What I was getting was that we found x to be = \(\cos(45) \cdot 18\) = \(\cfrac{\sqrt{2}}{2}\cdot 18\) = \(9 \sqrt{2}\) but that isnt one of your answers.

OpenStudy (bahrom7893):

\[Cos(45°)= \frac{x}{18}\]\[x=18*\frac{\sqrt{2}}{2}=9*\sqrt{2}\]

OpenStudy (bahrom7893):

That is correct. The question's wrong.

OpenStudy (bahrom7893):

Well the given choices might be wrong

OpenStudy (jhannybean):

Yeah... That's what I was thinking.

OpenStudy (anonymous):

ya it is right thanks you guys

OpenStudy (jhannybean):

no problem

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