**Trigonometry Formulas for class 11 **

**(PDF download)**

Trigonometry is quite an interesting subject. Here are the useful Trigonometry Formulas for class 11 Maths

**Basic Formula**

$tan(x) = \frac {sin(x)}{cos(x)}$

$cot(x) = \frac {cos(x)}{sin(x)}$

**Reciprocal Identities:**

$cosec(x) = \frac {1}{sin(x)}$

$sec(x) =\frac { 1}{cos(x)}$

$cot(x) = \frac {1}{tan(x)}$

$sin(x) = \frac {1}{cosec(x)}$

$cos(x) = \frac {1}{sec(x)}$

$tan(x) = \frac {1}{cot(x)}$

**Pythagorean Identities:**

$sin^2(x) + cos^2(x) = 1$

$cot^2x +1 = cosec^2x$

$1+tan^2x = sec^2x$

**Trigonometric Ratio’s of Common angles**

We can find the values of trigonometric ratio’s various angle

**Trigonometry Formula for Complementary and supplementary angles**

__Sin and cos function__

- $cos(A+B)=cos(A)cos(B)-sin(A)sin(B)$
- $cos(A-B)=cos(A)cos(B)+sin(A)sin(B)$
- $cos(\pi /2 -A)=sin(A)$
- $sin(\pi /2 -A)=cos(A)$
- $sin(A+B)=sin(A)cos(B)+sin(B)cos(A)$
- $sin(A-B)=sin(A)cos(B)-sin(B)cos(A)$

__Tan and cot functions__

If none of the angles x, y and (x + y) is an odd multiple of $\pi /2$

$tan(A+B)=\frac{tan(A)+tan(B)}{1-tan(A)tan(B)}$

$tan(A-B)=\frac{tan(A)-tan(B)}{1+tan(A)tan(B)}$

If none of the angles x, y and (x + y) is a multiple of $\pi /2$

$cot(A+B)=\frac{cot(A)cot(B)-1}{cot(A)+cot(B)}$

$cot(A-B)=\frac{cot(A)cot(B)+1}{cot(B)-cot(A)}$

**Some more Trigonometric Functions**__Double of x (Double Of Angles)__

$cos2x=cos^{^{2}}x-sin^{^{2}}x=2cos^{^{2}}x-1=1-2sin^{^{2}}x=\frac{1-tan^{^{2}}x}{1+tan^{^{2}}x}$

$sin2x=2cos(x)sin(x)=\frac{2tan(x)}{1+tan^{^{2}}x}$

$tan2x=\frac{2tan(x)}{1-tan^{^{2}}x}$

__Triple of x ( Triple of Angles)__

$sin3x=3sin(x)-4sin^{3}x$

$cos3x=4cos^{3}x-3cos(x)$

$tan(3x)=\frac{3tanx-tan^{^{3}}x}{1-3tan^{^{2}}x}$

**Sum and Difference of Angles**

$cos(A)+cos(B)=2cos\frac{A+B}{2}cos\frac{A-B}{2}$

$cos(A)-cos(B)=-2sin\frac{A+B}{2}sin\frac{A-B}{2}$

$sin(A)+sin(B)=2sin\frac{A+B}{2}cos\frac{A-B}{2}$

$sin(A)-sin(B)=2cos\frac{A+B}{2}sin\frac{A-B}{2}$

**Half Angle Formula**

**Pythagoras’ Identities in Radical form**

**Power Reducing Functions**

**Trigonometric equations Formula’s**

1.$sin x = 0$ implies $x = n \pi$, where n is any integer<br>

2.$cos x = 0$ implies $x = (2n + 1)(\pi /2)$<br>

- $sinx =siny$ then $x=n \pi + (-1)^{n}y$ where n is any integer<br>
- $cosx=cosy$ then $x=2n \pi + y$ or $x=2n \pi – y$ where n is any integer<br>
- $tanx=tany$ then $x=n \pi +y$ where n is any integer<br>

5. Equation of the form

$sin^2x = sin^2 y, cos^2 x = cos^2 y , tan^2 x = tan^2 y$

The general solution is given by

$x = n \pi \pm y$ where n is any integer

6. Equation of the Form

|sin x|=1 ,General solution is given by $x= (2n+1) \frac {\pi}{2}$<br>

|cos x|=1, general solution is given by $x=n \pi$<br>

**Some basics Tips to solve the trigonometry questions**

(1) Always try to bring the multiple angles to single angles using the basic formula. Make sure all your angles are the same. Using $sin(2x)$ and $sin(x)$ is difficult, but if you use $sin(2x) = 2 sin(x)cos(x)$, that leaves $sin(x)$ and $cos(x)$, and now all your functions match. The same goes for addition and subtraction: don’t try working with $sin(x+y)$ and $sin (x-y)$. Instead, use $sin(X+Y) = sin(x)cos(y)+cos(x)sin(y)$ so that all the angles match

(2) Converting to sin and cos all the items in the problem using a basic formula. I have mentioned sin and cos as they are easy to solve. You can use any other also.

(3)Check all the angles for sums and differences and use the appropriate identities to remove them.

(4) Use Pythagorean identifies to simplify the equations

(5) Practice and Practice. You will soon start figuring out the equation and their symmetry to resolve them fast

Download all the trigonometry Formulas below

Hope you like this compilation of Trigonometry Formulas for class 11. This will be very useful for the Maths students

## Download Trigonometry Formulas PDF

**Related Links**

Trigonometric functions

Domain ,Range and Graphs of Trigonometric functions

Trigonometric equations

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Important trigonometry questions for class 11 Maths

how to remember trigonometry table easily

https://en.wikibooks.org/wiki/Trigonometry/Remembering_Trig_Formulae

SridharanOf great help. If only can be made in down loadable PDF format..

physicscatalystHi pdf download is available after related links at the end of the article. I’ll highlight it so that it become more visible. Thanks

TANMAY PANDATrigonometry

Harita6×cos2x+sin2x

Mohammad Affanthis compilation of formulas was really helpfull. In my opinion some examples should also be added in order to clear some basic doubts.

Rajkishore NemchandWill appreciate to be explained which formula or identity to use and when solving equations.

Thnaks and looking forward to hear from you soon.

Amit kumarHelful formula.

...Sir great help….

Pls tell ur name

Chinmay NiralaVery good website

kiransir it would be great if a last summery page of main formulas to be added

JepomasThis website is helfpul for all the students