# Thread: Angle problem: Changing algebric expressions to angles

1. ## Angle problem: Changing algebric expressions to angles

We prefer that the answers are defined in RR to the second power (I don't know what RR to the second power means). Answer graphically each answer in the same cartesian coordinate system.
f(x)=2x
h(x)=2x+2
g(x)2x-1
i(x)=2x-4

2. Originally Posted by Julian.Ignacio
We prefer that the answers are defined in RR to the second power (I don't know what RR to the second power means). Answer graphically each answer in the same cartesian coordinate system.
f(x)=2x
h(x)=2x+2
g(x)2x-1
i(x)=2x-4
This question is still not clear. Please state clearly what Changing algebric expressions to angles is meant to mean. Do you mean find the angle the line makes with the x-axis?

3. Yes...I'm sorry Mr.Fantastic, I study math in french so I gotta like translate some words which makes it hard for me to explain ;P, and yes an x-axis..sorry.

4. In a line $y=mx+b$, $m=\tan \theta$, $\theta$ is the angle between the line and the positive direction of the x-axis.

Here is a formula for you.

Given that $\theta$ is the angle formed from the line $y=mx+b$ to line $y=m'x+b'$, then

$\tan\theta=\frac {m'-m}{1+mm'}$

5. Originally Posted by Julian.Ignacio
We prefer that the answers are defined in RR to the second power (I don't know what RR to the second power means). Answer graphically each answer in the same cartesian coordinate system.
f(x)=2x
h(x)=2x+2
g(x)2x-1
i(x)=2x-4
The statement of that question is totally incomprehensible as far as I am concerned.

6. Originally Posted by chengbin
In a line $y=mx+b$, $m=\tan \theta$, where $theta$ is the angle. Mr F adds: Between the line and the positive direction of the x-axis.

Here is a formula for you.

Given that $\theta$ is the angle formed from the line $y=mx+b$ to line $y=m'x+b'$, then

$\tan\theta=\frac {m'-m}{1+mm'}$
..