Question

How to find the exact value of sec(13pi/6)

Answer 1

`\frac{13\pi}6\equiv\frac\pi6\mod2\pi` (in other words, they represent the same angle on the unit circle)

So,


`\sec\frac{13\pi}6=\sec\frac\pi6=\frac1{\cos\frac\pi6}`

You have
`\cos\frac\pi6=\frac{\sqrt3}2`, so
`\sec\frac\pi6=\frac{\sqrt3}2`