# Does straight lines have slopes of tanget?

1. Oct 23, 2004

### Tanya Back

Does straight lines have slopes of tangent?

Does straight lines have slopes of tangent?.. i had no clue when this question came on a test..so i just left it...do they?..i just thought maybe they didn't since they have no limit. Hope i get an answer for this question.

Tanya

Last edited: Oct 23, 2004
2. Oct 23, 2004

### maverick280857

A straight line has the equation

$$y = mx + c$$

here m is called its slope and c is the y-intercept. If you do not know, then this is a formula relating the y-coordinate of a point on the line to its x-coordinate (remember there must be a specific relationship between the x and y coordinates of a point if it moves on a well defined non-arbitrary curve...in this case the curve is a straight line).

A straight line does have a tangent also called its slope. The important thing is that the slope of a straight line is constant (unlike that of other curves which may change from point to point...draw a diagram of a circle to convince yourself that this is so). Secondly, only two parameters are required to fix a straight line:

1. Two points or
2. One point and the slope
3. Slope and y-intercept

The more general equation of a straight line in the cartesian plane is

ax + by + c = 0

but as you can see, it can be transformed into the form mentioned above using simple algebraic manipulations.

Cheers
Vivek

3. Oct 23, 2004

### Hurkyl

Staff Emeritus
Every line is its own tangent line at each of its points.

4. Oct 23, 2004

### HallsofIvy

Staff Emeritus
I think what you mean is this: the slope of a straight line is the tangent of the angle the line makes with the x-axis. That is true.

5. Oct 23, 2004

### Tanya Back

Thank u guys!!!! I understand much better now..i wish i had asked this question before the test ..oh well.. anyways Thank u

Tanya