# Trigonometric formulas for tangent?

using those formulas, how would you solve
tan 11 pi
-----
8

and cot 195

also, how would you prove tan (x +y ) = tan x
and tan ( pi/4 -x) = 1 - tan x
---------
1 + tan x

thank you so much for any help

the -------------- and what's under that belongs on the right side of the equation

Integral
Staff Emeritus
Gold Member

Also I am moving this to the homework help forum, in the future please post this type of question there.

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latex is a good tool, im learnign it myself

HallsofIvy
Homework Helper
using those formulas, how would you solve
tan 11 pi
-----
8

and cot 195
It's really a very bad idea to mix radians and degrees which it looks like you are doing here. Do you know what tan($\pi/4$) is? Do you know the "half angle" formula for tangent?

also, how would you prove tan (x +y ) = tan x
You wouldn't- it's not true!

and tan ( pi/4 -x) = 1 - tan x
---------
1 + tan x
What is tan(x+ y)?? And what is tan($\pi/4$)?

thank you so much for any help[/QUOTE]