Question

What is the sec(inverse cos (5^0.5/2))?

Answer 1

`sec(arccos(sqrt(5)/2))=2/sqrt(5)`

Explanation:

For this problem, we just need two facts:

• `sec(x) = 1/cos(x)` (by definition of the secant function)

• `cos(arccos(x)) = arccos(cos(x)) = x` (by definition of the inverse of a function)

Applying those gives us

`sec(arccos(sqrt(5)/2)) = 1/cos(arccos(sqrt(5)/2)) = 1/(sqrt(5)/2) = 2/sqrt(5)`