4 ms·

How does cos(theta) produce irrational values for 60 deg <= theta <= 90 deg?

• Mi_Ka_ 10y ago
  That is what I knew. For example- cos 75 = (√2(√3 – 1))/4 For testing you can visit here- http://www.webconversiononline.com/trigonometry-calculator.aspx?anglein=degree&type=cosine&of=85 http://www.webconversiononline.com/trigonometry-calculator.a...
  • nanis 10y ago
    cosine is a continuous function. Rationals are dense in reals etc. eg, arccos(1/3)
    • Mi_Ka_ 10y ago
      Yes, arccos(1/3) = 70.5287794 degrees
      • gus_massa 10y ago
        The important point is that cos(arcos(1/3)) = cos(70.5287794... degrees) = 1/3 that is a rational value.
  • deleted 10y ago
    [deleted]