Trigonometry with an inclined plane

[bdolle]

<Moderator's note: Moved from a technical forum and therefore no template.>

I don't understand the math here which is troubling considering I got A's in calc 2 and 3...

I tried to divide both sides by cos(theta) and solve for tantheta. but that gives something different.

Also, what does tantheta>=1 even mean? Is this second quadrant or fourth quadrant?

Thanks!

 

[bdolle]

Nevermind. Got the equation for the tan>1 case (I was thinking tan>0 or tan<0 not 1).

But for the case where tan of theta is less than one, that would mean between pi/4 and pi/2. I'm wondering why sintheta becomes negative and costheta becomes positive.

Any takers?

 

[haruspex]

where tan of theta is less than one, that would mean between pi/4 and pi/2.

Between -π/2 and π/4.