Let us understand the trigonometric ratios of (90+θ),(90-θ),(180+θ),(180-θ)etc. In addition I have provided all these ratios in a single picture.

In the previous posts, we have learned the signs of trigonometric ratios in various quadrants.[Signs of trigonometric functions in various quadrants]

NOTE that, the trigonometric ratios **changes** in** (2n+1)\frac { \pi }{ 2 } ±θ i.e**

**sin**changes to**cos**or vice versa**cosec**changes to**sec**or vice versa**tan**changes to**cot**or vice versa

For example, sin (90+θ)=cosθ

and cos(90+θ)=-sinθ

It is equally important to know that the **s****igns of the trigonometric ratios will depend upon the quadrants.**

Also, there is **no change in the trigonometric ratios** in **(nπ±θ)**

Another example, sin(180+θ)=-cosθ and sec (360-θ)=secθ

Recalling the signs of trigonometric ratios in various quadrants-

** All trigonometric functions in the first quadrant are positive. **

** In 2nd quadrant only sin and cosec are positive. **

** Under the 3rd quadrant only tan and cot are positive. **

** In the fourth quadrant only cos and sec are positive. **

With this in mind have a look at the image below.

This image will be beneficial for finding trigonometric ratios of 90+θ,90-θ,180+θ etc.

You can also visit the page where I have provided all trigonometric formulas.

Mohit Sharma.ksj@gmail.comMy self mohit sharma…. Thanx for giving us so precious information….

priya0693Thank you for this appreciation, means a lot to me.

whencutwow great one

YashavanthThanks for the information. Easy to learn