# Trignometric simple function:-

1. May 7, 2014

### Huygen121

Can you please tell me the reason behind this relation:-

y=tanx

Domain:-

R-{(n*180) + 180/2),n ε Z(integers))}

but how can n belong to integer because if n belong to integer than an angle would be negative and i dont think so that negative angles are there,i think that in place of (integers),natural nos. should come.but why they dont put natural nos. in place of integers,there??

2. May 7, 2014

### Mentallic

Of course there are negative angles. All trig functions extend infinitely in the positive and negative directions.

3. May 7, 2014

### Huygen121

can you give me an example related to it by just using the tan x and putting value in it?

4. May 7, 2014

### Huygen121

can the tan of an angle be negative,if so,then how?

5. May 7, 2014

### jbriggs444

You can use a calculator. Select degree mode if needed. Input -45. Press TAN. The result should be -1.

Physically, this would correspond to pointing your arm at an object that is 100 feet away horizontally and 100 feet down vertically. The angle is 45 degrees below horizontal and the tangent of the angle is the result of dividing the opposite side (-100 feet vertical) by the adjacent side (100 feet horizontal).

6. May 7, 2014

### Huygen121

but what exactly (-) minus sign indicates as we know dimensions are same to + angle ?

7. May 7, 2014

### Staff: Mentor

Because an angle can be negative. An angle is defined by two rays that extend from a common point. In mathematics, the starting ray usually extends out along the x-axis. If you rotate a terminal ray counterclockwise, you get a positive angle. If you rotate the terminal ray clockwise, you get a negative angle.

8. May 7, 2014

9. May 8, 2014

### Huygen121

what is the use of negative axis in graph? simple question and it will clear my all doubts

10. May 8, 2014

### Mentallic

It sounds as though you have a problem with negative numbers in general. The negative axis on a graph is there because negative numbers exist as much as the positive numbers exist.