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  1. Nov 6, 2005 #1
    I am very confused with this SOH CAH TOA problem.:confused:
    sin30 = O/H
    and what do you do when you are looking for Hypoteneuse ,
    sin30 = 5/H
    Like that, the answer is 10 but i really dont know how i should do this.
    I tried sin30/5 and it didn't come out right, so HELP!:confused:
  2. jcsd
  3. Nov 6, 2005 #2
    thanks a lot :)
  4. Nov 6, 2005 #3
    The answer is 10. The sin function represents a ratio of sides, for this one, the opposite and hypotenuse post. sin(30) is always one half, regardless of the side lengths. So if the angle is 30 deg, and the opposite side is 5, then the sin function will give you the hypotenuse length because it gives you the ratio of one to the other.

    If [itex] \sin 30 = \frac{1}{2} [/tex] then you can just say [itex] \frac{1}{2} = \frac{5}{H} [/tex]
    Last edited: Nov 6, 2005
  5. Nov 6, 2005 #4
    know the unit circle? know how trig relates to triangles? thats how you should solve this problem, sohcahtoa is a crutch.
  6. Nov 7, 2005 #5


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    Do you mean you want to find the hypotenuse?
    If so:

    sin 30 = O/H
    multiply both sides by H to give,
    H sin 30 = O
    then divide both sides by sin 30 to give
    H = O/sin 30

    Not sure if that what you meant though?
  7. Nov 9, 2005 #6


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    Was your calculator in degrees mode or radians mode?

    If your calculator is in radians mode, you found the sine of 30 radians, or about 1719 degrees, which is definitely different than the sine of 30 degrees.(That tends to be the most common mistake)
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