# Need assistance with Maths again

**URL:** <https://forum.kirupa.com/t/need-assistance-with-maths-again/53667>\
**Category:** random\
**Created:** [June 6, 2004, 11:11am UTC](https://forum.kirupa.com/t/need-assistance-with-maths-again/53667 "2004-06-06T11:11:24Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![minimalistik](https://avatars.discourse-cdn.com/v4/letter/m/e47774/32.png) [@minimalistik](https://forum.kirupa.com/u/minimalistik)\
**Post date:** [June 6, 2004, 11:11am UTC](https://forum.kirupa.com/t/need-assistance-with-maths-again/53667/1 "2004-06-06T11:11:24Z")

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Hey again,

Yes i have some problems with questions about Trig. Functions again and im planning to make it a regular thing if posting on the forum is my last resort if you guys dont mind. Here are the questions:

1. cos ( pi /4 + x ) is the identity of 1 / root 2 (cos x - sin x)

2. cos (a + b ) . cos (a + b) is the identity of cos squared a - sin squared b

Can somebody assist me?