Question #c1993

Question

1291 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2017-03-04T22:20:18

Many calculators don't have a $sec^-1$ button. So, if we want to evaluate $sec^-1(8)$ , we'll have to rewrite it.

First, let:

$sec^-1(8)=theta$

Via the definition of inverse functions:

$8=sec(theta)$

Since secant and cosine are reciprocals:

$1/8=cos(theta)$

Then:

$cos^-1(1/8)=theta$

Thus:

$sec^-1(8)=cos^-1(1/8)$

Which can be plugged into a calculator.