trig Identities 7

Mathematics
Tutor: None Selected Time limit: 1 Day

Find the exact value for .cos(-390)

Dec 17th, 2014

  • - square route of 3/2
  •  Use the identity for negative angles, to write 

    sin (- Pi / 3) = - sin (Pi / 3) 
  • Pi / 3 is in quadrant 1 and there is no need for either coterminal or reference angles. sin (- Pi / 3) is evaluated directly as follows 

    sin (- Pi / 3) = - sin (Pi / 3) = - sqrt (3) / 2

Dec 17th, 2014

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Dec 17th, 2014
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Dec 17th, 2014
Dec 5th, 2016
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