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

Asked on by agvickers

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nathanshields | High School Teacher | (Level 1) Associate Educator

Posted on

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.


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agvickers | Student, Grade 11 | (Level 1) Honors

Posted on

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...


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