Solving a Trigonometry Problem with Tan A and Tan B

[Davidmb19]

Homework Statement

The lines L1 and L2 with equations y=2x and 3y=x-1 respectively,are drawn on the same set of axes. Given that the scales are the same on both axes and that the angle L1 and L2 make with the positive x-asis are A and B respectively,

write down the value of Tan A and the value of Tan B

Homework Equations

Tan=O/A

The Attempt at a Solution

I've figured out tanA which is 2. Why? It doesn't matter what value of x you substitute into L1 you'll always get 2 when you do O which is Y divide by A which is X. I'm using tan=o/a. But, I do not know how to get tan B; it isn't the same thing.

 

[CWatters]

The general (or standard) equation for a straight line is y = mx + c where

m is the slope = Δy/Δx = Tanθ
and c is a constant.

So comparing that with y=2x it's clear that m=2 (and c=0).

I suggest you rearrange the other equation (3y=x-1) into the standard form for a straight line and work out the slope m.

 

[Davidmb19]

Δy/Δx = Tanθ << Ahh you're right. I never noticed even though I used the same method.Silly me. Thanks