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Exact values of sin(30) and cos(3pi/2)

  1. Sep 25, 2005 #1
    How can I work out exact values for trig functions like sin(30) and cos(3pi/2)?
  2. jcsd
  3. Sep 25, 2005 #2
    For simple expressions, use trigonometric/complex identities to reduce to terms you already know. For more complicated expressions, use series, ie., Taylor or Euler's expansions.
  4. Sep 25, 2005 #3
    Like the decimal values? Without a calculator?

    I would just draw out the triangle and leave the answer in the exact radical form, like in your first example. But [itex]\cos{\frac{3\pi}{2}}[/itex] is 0 so that should be easy.
  5. Sep 25, 2005 #4
    Ah thanks.
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