Secant of 60 Degrees

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Theorem

$\sec 60 \degrees = \sec \dfrac \pi 3 = 2$

where $\sec$ denotes secant.


Proof

\(\displaystyle \sec 60 \degrees\) \(=\) \(\displaystyle \frac 1 {\cos 60 \degrees}\) Secant is Reciprocal of Cosine
\(\displaystyle \) \(=\) \(\displaystyle \frac 1 {\frac 1 2}\) Cosine of $60 \degrees$
\(\displaystyle \) \(=\) \(\displaystyle 2\) multiplying top and bottom by $2$

$\blacksquare$


Sources