You can't. There is an expression for it, but it involves complex numbers and you can't
really compute the value without a calculator.
really compute the value without a calculator.
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Usually, you start with known values, like cos(60) =1/2 or sin(30) = 1/2 or sin(45) = sqrt(2)/2
and find an identity that works (60 = 3 * 20, for example, or 60 = 45 + 30/2)
But it's often a lot easier to look up the values in a table or using a calculator.
and find an identity that works (60 = 3 * 20, for example, or 60 = 45 + 30/2)
But it's often a lot easier to look up the values in a table or using a calculator.
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Use the Maclaurin series of Cos(x) or Sin(x).... If you feel like doing it!