# Arccos(tan(3pi/4) is coming out undefined when it should be pi

**URL:** <https://cl.desmos.com/t/arccos-tan-3pi-4-is-coming-out-undefined-when-it-should-be-pi/4700>\
**Category:** Bug Reports\
**Created:** [February 4, 2023, 7:53am UTC](https://cl.desmos.com/t/arccos-tan-3pi-4-is-coming-out-undefined-when-it-should-be-pi/4700 "2023-02-04T07:53:31Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![ANDREW\_VU](https://yyz1.discourse-cdn.com/flex031/user_avatar/cl.desmos.com/andrew_vu/32/4120_2.png) [@ANDREW\_VU](https://cl.desmos.com/u/ANDREW_VU)\
**Post date:** [February 4, 2023, 7:53am UTC](https://cl.desmos.com/t/arccos-tan-3pi-4-is-coming-out-undefined-when-it-should-be-pi/4700/1 "2023-02-04T07:53:31Z")

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Something’s not working the way it seems like it should.

When I … typed in arccos(tan(3pi/4) it resulted in undefined

I saw …

But I expected … pi

Here’s the link to the page, dashboard, or activity:

And here are some screenshots or a video:

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**Author:** ![JayChow](https://yyz1.discourse-cdn.com/flex031/user_avatar/cl.desmos.com/jaychow/32/1674_2.png) [@JayChow](https://cl.desmos.com/u/JayChow)\
**Post date:** [February 4, 2023, 4:56pm UTC](https://cl.desmos.com/t/arccos-tan-3pi-4-is-coming-out-undefined-when-it-should-be-pi/4700/2 "2023-02-04T16:56:12Z")

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