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.