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Thread: Sine, Cosine and Tangent... uses?

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    Default Sine, Cosine and Tangent... uses?

    I know for the majority how to obtain the sine cosine and tangent, but what are they actually used for?

    My school blew me off (8th grade), my parents don't know. So I'm coming to you guys. I know I am a bit young but can someone at least try to explain stuff like this?



    Also, I've never fully understood all the compass type procedures, with the Radians and angles and what not... Anyone on MSN who can 'tutor' me? :P


    Thanks in advance,
    ~Abyssal

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    Whoa, you don't know how long I've wanted to know this. My parents tried to explain it, but they were using tons of terms I don't know. 7th grade

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    Yea, so being 14 I asked my math teacher and her response was "You wont understand it". So that was special.

    Perhaps we can learn together then?

    HOWEVER: I'm not dumb when it comes to math, so I'm not that slow.

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    Alright Ill try to explain it. (11th Grade)
    give me a few mins to draw up some diagrams.


    What you probably need to know first though is what you would use cosine, sine and tangent for.
    Its used for finding the unknown side of a right-angled triangle.
    You will need to know at least 1 angle and 1 side for it to work.

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    So which rule do we use to find side X?
    Sine, Cosine or Tangent?

    Remember this rule. SOH CAH TOA.
    This means,

    Sine = Opp/Hyp

    Cos = Adj/Hyp

    Tan = Opp/Adj


    We are trying to find the Opposite side, so we can use rules Tan and Sine.
    We already know the Adjacent side, so what rule uses the Opposite and Adjacent Sides?
    Tangent does.

    For this bit you will need to know simple algebra.
    You put the angle after the Tan in the equation.

    Tan = Opp/Adj
    :.
    Tan48 = X / 50
    :.
    50*Tan48=X
    :.
    X = 55.53
    (thats what my calculator tells me anyway)

    And that’s all it is, now enter in your calculator 58*Tan48
    And you will get what X is equal too!!

    Hooraa!

    Lol does that make any sense to you at all?

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    With Sine, Cosine and tangent you can calculate triangle's sides and angle degrees.

    And btw, I think correct answer is 47m
    When I die will they remember not what i've done but what I haven't done?
    It's not the end that i fear with each breath,
    it's life that scares me to death
    -------------------------------
    http://www.secetweb.com

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    Lol thanks Secet, i see where I made an error.

    EDIT: Hmm after fixing my error I get 55.53?
    What did you do?

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    Tangent 48 degrees = x/50
    Tan 48 degrees * 50 = x
    x = tan48 * 50
    x = 55,53m :P

    Sorry I was mistaken also, somehow :P
    When I die will they remember not what i've done but what I haven't done?
    It's not the end that i fear with each breath,
    it's life that scares me to death
    -------------------------------
    http://www.secetweb.com

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    the ratios of a curve line

    http://www.villavu.com/forum/showthread.php?t=8442

    this kinda helps you see the diffrences between sin/cos
    play it in SCAR and mess with the const

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    As for use in circles:



    Lets say you know the coords of the center dot, and you want to find the coords of all the points on the circle. You know the radius.

    Imagine a hexagon, 6 points, 6 sides. Now add 2 points and sides, make it an octagon, keep it the same 'radius'. There are now more sides, and they are smaller. Keep doing this, and eventually it will look like a circle, although it will be many many points, connected by that many tiny lines. So for our circle, we figure out the coords of a bunch of points, lets say 360 to make it easy, one for each degree.

    Now in the diagram above, the angle looks close to 45 degrees, but pretend it's 1 degree. So we need to get the coords of the first point, the red dot. We know the coords of the black dot, so we just need the difference in X and the difference in Y.

    The difference in X is the length of the orange line, and for Y its the green line. Combine these 2 with a radius (blue line) you get a nice right angle triangle, which you can use SOH CAH TOA with.

    The angle is 1 degree. The hypotenuse is the blue line (opposite the right angle), the orange line is the opposite (opposite the angle we know*), and green is adjacent (next to the angle we know).

    Sin(1)=orange/blue
    orange=Sin(1)*blue

    Cos(1)=green/blue
    green=Cos(1)*blue

    So now you know the difference between the center coords and the point on the circle. Repeat this for 360 degrees, and you get 360 points on the circle. Which for our uses, is probably enough to be close enough so that it looks like a smooth circle.



    *(yea I know you can do 90-D to get the other one, but we are going use the angle in the middle)

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    Thanks for all the help guys, I somewhat understand it now :P

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