how do you solve problems like: cos[arctan(-1)] ?? thanks everyone

Expert Answers
nathanshields eNotes educator| Certified Educator

1. Tangent of what angle is -1?
2. What is cosine of this angle?

The tangent function is like the slope of a radius on the unit circle.  There are two that have a slope of -1: `135^o` and `315^o`

Let's just use the first one: `135^o` or `(3pi)/4` radians.

Take the cosine (visualize the adjacent and hypotenuse: `-sqrt(2)/2` and `1` ), and your answer is


Notice that if you used the other angle, your answer would be


So you check what domain you want your answer to be in.


agvickers | Student

in the problem all i was given was this, and it wants me to use the properties of inverse functions......i dont really understand it yet...


Access hundreds of thousands of answers with a free trial.

Start Free Trial
Ask a Question