# Help me figure out an trig formula in Excel

**URL:** <https://boards.straightdope.com/t/help-me-figure-out-an-trig-formula-in-excel/471380>\
**Category:** Factual Questions\
**Created:** [November 6, 2008, 12:12am UTC](https://boards.straightdope.com/t/help-me-figure-out-an-trig-formula-in-excel/471380 "2008-11-06T00:12:54Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![commasense](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/commasense/32/3017_2.png) [@commasense](https://boards.straightdope.com/u/commasense)\
**Post date:** [November 6, 2008, 12:12am UTC](https://boards.straightdope.com/t/help-me-figure-out-an-trig-formula-in-excel/471380/1 "2008-11-06T00:12:54Z")

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[This Web site](http://myhometheater.homestead.com/viewingdistancecalculator.html) has a calculator that allows you to find the viewing angle for a given size TV screen as seen from a given distance. I’d like to be able to incorporate the same function in a spreadsheet.

The only problem is that I never took trig, and don’t have time (or need or inclination) to take a crash course now, just for this little task, if one of you math whizzes will help me.

What I need is a formula that yields “Current Viewing Angle” (the first field under “Results”) given the “Distance to main viewing location” (call it cell A1) and the “Screen Width” (cell A2).

The Web site has you input “Distance” in feet and “Screen Width” in inches, since that’s the most common situation for home theaters. But I would rather have the same units in both cells.

Thanks.

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**Author:** ![YamatoTwinkie](https://avatars.discourse-cdn.com/v4/letter/y/cc9497/32.png) [@YamatoTwinkie](https://boards.straightdope.com/u/YamatoTwinkie)\
**Post date:** [November 6, 2008, 1:33am UTC](https://boards.straightdope.com/t/help-me-figure-out-an-trig-formula-in-excel/471380/2 "2008-11-06T01:33:11Z")

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=2\*degrees(atan((a2/2)/a1))

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**Author:** ![YamatoTwinkie](https://avatars.discourse-cdn.com/v4/letter/y/cc9497/32.png) [@YamatoTwinkie](https://boards.straightdope.com/u/YamatoTwinkie)\
**Post date:** [November 6, 2008, 1:41am UTC](https://boards.straightdope.com/t/help-me-figure-out-an-trig-formula-in-excel/471380/3 "2008-11-06T01:41:49Z")

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Just making sure: By “screen width”, you mean horizontal width, not diagonal width, right?

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**Author:** ![commasense](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/commasense/32/3017_2.png) [@commasense](https://boards.straightdope.com/u/commasense)\
**Post date:** [November 6, 2008, 4:28am UTC](https://boards.straightdope.com/t/help-me-figure-out-an-trig-formula-in-excel/471380/4 "2008-11-06T04:28:00Z")

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Excellent! Thanks, **YamatoTwinkie**! That’s perfect!