Exact trigonometric values

In mathematics, the values of the trigonometric functions can be expressed approximately, as in cos ⁡ ( π / 4 ) ≈ 0.707 {\displaystyle \cos(\pi /4)\approx 0.707} , or exactly, as in cos ⁡ ( π / 4 ) = 2 / 2 {\displaystyle \cos(\pi /4)={\sqrt {2}}/2} . While trigonometric tables contain many approximate values, the exact values for certain angles can be expressed by a combination of arithmetic operations and square roots.

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