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Why am I getting a different answer for this trig function than my textbook

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I am working through the following problem in my Physics text book: enter image description here
When I try to calculate the degrees with Wolfram I get a different answer then the text book: enter image description here
Why is this and how can I fix it?

POSTED BY: Tyler H
Answer
19 days ago

It should have been arctan, not tan.

POSTED BY: Gianluca Gorni
Answer
19 days ago

First of all, you would need arctan, not tan. Second, you can't just divide these two, this only works in the first quadrant.You're in the third quadrant. Arctan on wolfram alpha and Mathematica (wolfram language) can also accept x and y separately:

https://www.wolframalpha.com/input/?i=arctan(-3.5,-2.5)+in+degrees

which will give -144.5 degrees, or equivalently -144.5+360 = 216 degrees

Read the last line of your book carefully to understand why x/y does not work in this quadrant.

POSTED BY: Sander Huisman
Answer
19 days ago

Group Abstract Group Abstract