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Mathematics 6 Online
NotJay:

The legs of a right triangle measure 5 inches and 7 units. if \(\theta\) is the angle between the 5-inch leg and the hypotenuse, cos \(\theta\) = ___.

NotJay:

@dude

dude:

Pythagorean Theorem to find hypotenuse \(a^2+b^2=c^2\) Do you want assistance or the answer? ( ͡° ͜ʖ ͡°)

NotJay:

Options: 0.07, 0.81, 0.58, and 0.71

NotJay:

The answer le ( ͡° ͜ʖ ͡°)

dude:

|dw:1518134562394:dw|

dude:

That goes against the rules though ( ͡° ͜ʖ ͡°)

NotJay:

Curses (ಥ ͜ʖಥ)

dude:

\(5^2+7^2=c^2\)

NotJay:

That would be... 74?

NotJay:

did I take a wrong turn at Albuquerque?

dude:

Alberqueque?

NotJay:

Have you seriously never watched bugs bunny? https://www.youtube.com/watch?v=e8TUwHTfOOU

dude:

\(5^2+7^2=c^2\\ 25+49=c^2\\ 74=c^2\) root on both sides \(\large{\pm\sqrt{74}=c}\)

dude:

Hey, lets keep this on math ( ͡° ͜ʖ ͡°)

NotJay:

Right ( ͡° ͜ʖ ͡°)

NotJay:

Now what? o-o

dude:

|dw:1518134835889:dw|

dude:

The 5 and 7 could be on either side

NotJay:

mfw the 7 is shorter

dude:

Disclaimer: This is not drawn to scale

NotJay:

LOL

dude:

We can use cosine \(cos(x)=\frac{Adjacent}{Hypotenuse}\)

NotJay:

*head explodes*

dude:

\(cos(\theta)=\frac{5}{\sqrt{74}}\)

NotJay:

Ah ok, forgot what adjacent meant there

dude:

That is nice (ಥ ͜ʖಥ)

NotJay:

So 0.58 is my answer?

dude:

How did you get that?

NotJay:

\(5\div\sqrt{74}\) \(\sqrt{74}=8.60\) \(5\div8.60=0.58\)

dude:

You have \(cos(\theta)=0.58\) Theta is still not isolated you have to do the opposite of cos Dont know how to explain this x.x

NotJay:

@563blackghost I see you viewing the post, can you explain it? O-o

563blackghost:

dude is doing pretty well in my opinion.

563blackghost:

Do you know your ratios? for sin, tan, cos?

NotJay:

Not really no x.x

dude:

ಠ_ಠ

563blackghost:

You need to know your ratios before actually completeing this problem.

563blackghost:

How about the format of Pythagorean Theorem?

NotJay:

Do you mean \(a^2+b^2=c^2\)?

563blackghost:

yesh dat :3

dude:

Do you know what theta is? ಠ_ಠ

NotJay:

How did you guess I didn't? ಠ_ಠ

dude:

Continue ghost >.<

563blackghost:

okay...

563blackghost:

Sorry I wrote the last part wrong.... So let's draw our right triangle.... |dw:1518136233138:dw| There are three ratios for a right triangle.... \(\large\bf{\sin (x)=\frac{opposite}{hypotenuse}}\) \(\large\bf{\tan (x)=\frac{adjacent}{hypotenuse}}\) \(\large\bf{\cos (x)=\frac{adjacent}{hypotenuse}}\)

563blackghost:

Each ratio is plugged according to a triangles angle or sides. |dw:1518136357057:dw| For example if we want to find the angle A we would use the sides around. We see we have a side x and a side y. `The hypotenuse will always be the hypotenuse`. So `side y` is the hypotenuse. Since `side x` is next to `angle A` it is our adjacent. Which ratio contains a hypotenuse and adjacent?

563blackghost:

sorry `side y` is meant to be typed as `side z`.

563blackghost:

For example if we want to find the angle A we would use the sides around. We see we have a `side x` and a `side z`. The hypotenuse will always be the hypotenuse. So `side z` is the hypotenuse. Since `side x` is next to` angle A` it is our adjacent. Which ratio contains a hypotenuse and adjacent?

563blackghost:

corrected paragraph above ^

NotJay:

\(\Large\frac{x+y}{z}\)?

563blackghost:

Close. `side y` is not included due to only using `2 sides` for a triangle ratio. So let's remove `side y`. \(\Large\bf{\frac{x}{z}}\) You formatted this correctly, which ratio is this identified as? `Sin, Tan, or Cos`?

NotJay:

Judging by what you posted before, tan or cos?

NotJay:

(although I'm assuming cos)

563blackghost:

Correct! Cosine!

563blackghost:

So we would follow as: \(\Large\bf{cos(\theta)=\frac{x}{z}}\) We would invert this so we can find the angle. \(\Large\bf{cos^{-1}(\frac{x}{z})=\theta}\) Do you understand the process to finding an angle?

NotJay:

Not really no

NotJay:

What is the -1 for in that equation? (and how is that calculated?)

563blackghost:

The `power of -1` is to invert the equation. That is all. This way you can plug it into your calculator.

dude:

\[2^{-1}=\frac{1}{2}\]

NotJay:

invert the equation...?

NotJay:

How does one turn a math equation inside out and dissect it? x'D

563blackghost:

by taking it to the power of -1.

dude:

\[2^{-2}=\frac{1}{4}\]

563blackghost:

For example the inversion of 2 is `1/2` if we multiply the two to each other we would get `1`.

NotJay:

*brain explodes* Does not compute... How does 2 = 1/2 what does inverting mean?

NotJay:

How do you calculate negative powers? O_o

563blackghost:

hmmmm Inversion means `to turn the opposite`. \(\large\bf{a^{-n}=\frac{1}{n}}\) This is the format of a number carried by a negative.

dude:

\[\frac{2}{1}=>\frac12\] or \(2^{-1}=\frac{1}{2}\)

NotJay:

Define opposite of a number? I can understand a... OH NOW THAT IT'S VISUALIZED I GET IT

563blackghost:

We invert the equation we got to find what `theta` is. \(\Large\bf{cos(\theta)=\frac{x}{z} \rightarrow cos^{-1}(\frac{x}{z})=\theta}\)

563blackghost:

Let's take your question now. We get that the legs are `5` and `7`. |dw:1518138010401:dw| We want to know the angle between `5` and the `hypotenuse`. |dw:1518138075064:dw| If we look at the triangle we see that `5 is the adjacent` and that `7 is the opposite`. Which ratio do we use?

NotJay:

Didn't we already determine it would be cosine? (sorry for disappearing, dinner was done)

563blackghost:

yes we did, but im trying to see if you understand after the ratios have been stated and an explanation of the use of it.

NotJay:

Does cosine equal what goes in the function? Or is there something else that goes on? If thats the case, didn't you define tan as the same as cos? Doesn't that mean you would end with the same exact result? PS: Sorry I'm so stupid x'D

563blackghost:

There are two ways you can solve your problem. You can solve by tan and/or cosine. @Dude solved by finding the hypotenuse and then used the length of the hypotenuse and the adjacent to find the angle. You can also use tangent by using the adjacent and the opposite. Either way will end up with the same solution.

NotJay:

So if I'm understanding this right, at this point, it's this? \(\Large^{-1}\frac{7}{5}\) or \(\Large\frac{5}{7}\) = \(\large5\div7\) Then from there I get 0.71... is that correct?

NotJay:

@563blackghost ?

NotJay:

>-< @dude ?

dude:

Welp I read this all wrong 5 and 7 are different units. I feel dumb

NotJay:

@velcolied

NotJay:

@vocaloid *

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