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Solving for Sin with no calculator

  1. Sep 4, 2014 #1
    Solving for Sin with no calculator + additional questions

    Untitled.jpg

    Sinθ=opp/hyp

    Sinθ=5/3

    Sinθ=1.6


    I know the answer is 35.87°. I would like to convert 1.6 to 35.87° but am unsure how.
     
    Last edited: Sep 4, 2014
  2. jcsd
  3. Sep 4, 2014 #2

    mathman

    User Avatar
    Science Advisor
    Gold Member

    Sinθ=3/5=0.6. You need a calculator or sine table.
     
  4. Sep 4, 2014 #3
    Oops!

    It's impossible to figure out? I am trying to prepare myself for the Accuplacer exam. Calculators are not allowed.
     
  5. Sep 4, 2014 #4

    Mark44

    Staff: Mentor

    This is not an angle that any reasonable person would expect you to know the sine, cosine, or other trig functions for. So finding that angle means that you'll need to use something to get an approximation; i.e., a calculator or table of trig functions.

    A more serious problem is that you misused the formula and calculated hyp/opp, instead of opp/hyp. Also, getting a value larger than 1 for the sine of an angle should have been a red flag. The values of sine and cosine are always between -1 and +1 for real number angles.
     
  6. Sep 4, 2014 #5

    Doug Huffman

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    Gold Member

    It's a 3-4-5 triangle. Might someone have suggested memorization of its Pythagorean Triple angles, similar to memorizing the unit circle functions?
     
  7. Sep 4, 2014 #6

    Mark44

    Staff: Mentor

    Not that I've seen in numerous precalc/trig textbooks. The usual angles to be memorized are 0°, 30°, 45°, 60°, and 90°, along with their counterparts in the other three quadrants.
     
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