# Math Help - arc tan, sin and cos

1. ## arc tan, sin and cos

ok
well my first questions dealing with inclination, i get how to do it though im having trouble calculating arctan.
so the question goes as follow

Find the inclination of the line 2x+3y=6.

***Solution****
tan(@)=-2/3
@=pie+arctan(-2/3)

though i cant calculate arctan of -2/3 so can someone explain me how to calculate arctan. thank you and if you can give me an inside for arc sin and cos that would be great thanks.

ok
well my first questions dealing with inclination, i get how to do it though im having trouble calculating arctan.
so the question goes as follow

Find the inclination of the line 2x+3y=6.

***Solution****
tan(@)=-2/3
@=pie+arctan(-2/3)

though i cant calculate arctan of -2/3 so can someone explain me how to calculate arctan. thank you and if you can give me an inside for arc sin and cos that would be great thanks.
so arctan is just the inverse of tangent. we use it to solve for an angle. so in general:

if sinx = y then x = arcsiny
if cosx = y then x = arccosy
if tanx = y then x = arctany
and so on

then you usually have to add k*pi, or 2k*pi depending on what interval you want to solve for and the particular problem. these functions are periodic, so they repeat the same values over and over, that's what the multiples of pi take care of

do you understand how they ended up with tan@ = -2/3?

ok
well my first questions dealing with inclination, i get how to do it though im having trouble calculating arctan.
so the question goes as follow

Find the inclination of the line 2x+3y=6.

***Solution****
tan(@)=-2/3
@=pie+arctan(-2/3)

though i cant calculate arctan of -2/3 so can someone explain me how to calculate arctan. thank you and if you can give me an inside for arc sin and cos that would be great thanks.
If your question is how to calculate arctan(-2/3) you need to do it on a calculator. There is no "nice" angle theta such that tan(theta) = -2/3.

-Dan

4. yeah i understand how they got tan(-2/3) but i have a bit of difficulty finding the arctan of it, but ill impliment what you stated and see what happens thanks. and how would i calculate it using the calculator

yeah i understand how they got tan(-2/3) but i have a bit of difficulty finding the arctan of it, but ill impliment what you stated and see what happens thanks. and how would i calculate it using the calculator
usually, the buttons that do the trig function do the inverse trig functions as second functions

so on your calculator, press 2ndF and then the button for tan and that will give you arctan or tan inverse, then enter the number you want