### Mathematics Class XI

Unit-I: Sets and Functions
Chapter 1: Sets
Unit-II: Algebra
Chapter 5: Binomial Theorem
Chapter 6: Sequence and Series
Unit-III: Coordinate Geometry
Chapter 1: Straight Lines
Chapter 2: Conic Sections
Unit-IV: Calculus
Unit-V: Mathematical Reasoning
Unit-VI: Statistics and Probability
Chapter 1: Statistics
Chapter 2: Probability

# Trigonometric Ratios and Trigonometric Functions

Let  be a right angled triangle, with let

Then, .

The lengths are known as respectively.

Definiton 1

(i)

(ii)

(iii)

(iv)

(v)

(vi)

We also defined:

(i)

(ii)

(iii)

(iv)

Definition 2

For angle-measure we defined:

,

,

are not defined.

Definition 3

For angle- measure we defined

are not defined.

Note:

have not defined as rations of lengths. So we do not use the term ‘trigonometric ratio’ for them. We shall replace the term by more general term ‘trigonometric function.’

Trigonometric Function for

Let denote respectively the x-coordinates and y-coordinates of a point whose polar coordinates are

Definitions

(i) Sine :

(ii) Cosine:

(iii) Tangent:

(iv) Cotangent:

(v) Secant:

(vi) Cosecant:

Note:

By taking in the above definitions we get the trigonometric functions from a unit circle.

Domain and Range of Trigonometric Functions

 Domain Range (i) (ii) (iii) (iv) (v) (vi)
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