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By ;- Soumyadeepta Roy
Class:- XI B
Roll no:- 31
Mathematics
INTRODUCTION
The word trigonometry is derived
from the Greek words trigon and
metron and it means measuring the
sides of a triangle
If in a circle of radius  r , an arc of
length  l  subtends an angle of
radians, then l = r
INTRODUCTION
 What about angles greater than 90属? 180属?
 The trigonometric functions are defined in terms of a
point on a terminal side
 r is found by using the Pythagorean Theorem:
22
yxr
RELATION BETWEEN
DEGREE AND RADIUS
1 radian= 180属/ =57属16
1属 = /180 radian
THE 6 TRIGONOMETRIC FUNCTIONS OF
ANGLE  ARE:
sin
y
r
 
cos 
tan  ,
sin 
0
0
0
csc ,
sec ,
cot ,
r
y
y
r
x
x
x
y
y
  
  
  0x
THE TRIGONOMETRIC FUNCTIONS
 The trigonometric values do not depend on the selected
point  the ratios will be the same:
First Quadrant:
sin  = +
cos  = +
tan  = +
cosec  = +
sec  = +
cot  = +
Mathematics
y
x
y
x
ALL STAR TRIG CLASS
 Use the phrase All Star Trig Class to
remember the signs of the trig functions in
different quadrants:
AllStar
Trig Class
All functions
are positive
Sine is positive
Tan is positive Cos is positive
The value of any trig function of an angle  is equal to
the value of the corresponding trigonometric function of
its reference angle, except possibly for the sign. The
sign depends on the quadrant that  is in.
So, now we know the signs of the trig
functions, but what about their values?...
REFERENCE ANGLES
 The reference angle, 留, is the angle between the
terminal side and the nearest x-axis:
ALL STAR TRIG CLASS
 Use the phrase All Star Trig Class to
remember the signs of the trig functions in
different quadrants:
AllStar
Trig Class
All functions
are positive
Sine is positive
Tan is positive Cos is positive
TRIGONOMETRIC IDENTITIES
 Reciprocal Identities
1
sin
csc
x
x

1
cos
sec
x
x

1
tan
cot
x
x

sin
tan
cos
x
x
x

cos
cot
sin
x
x
x

Quotient Identities
QUADRATIC ANGLES
(TERMINAL SIDE LIES ALONG AN AXIS)
THE VALUE OF TRIGONOMETRIC
FUNCTIONS FOR SOME COMMON
ANGLES.
0 /6 /4 /3 /2  3/2 2

0
遜 1/ 2 3 /2 1 0 -1 0
1 3 /2 1/ 2
遜 0 -1 0 1
0 1/ 3 1 3 Not
defined
0 Not
defined
0
sin
cos
tan
TRIGONOMETRIC IDENTITIES
2 2
1sin cosx x 
2 2
1 cot cscx x 
2 2
1tan secx x 
 Pythagorean Identities
 The fundamental Pythagorean identity:
 Divide the first by sin2x :
 Divide the first by cos2x :
TRIGONOMETRIC IDENTITIES
TRIGONOMETRIC IDENTITIES
THANK
YOU

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Mathematics

  • 1. By ;- Soumyadeepta Roy Class:- XI B Roll no:- 31
  • 3. INTRODUCTION The word trigonometry is derived from the Greek words trigon and metron and it means measuring the sides of a triangle If in a circle of radius r , an arc of length l subtends an angle of radians, then l = r
  • 4. INTRODUCTION What about angles greater than 90属? 180属? The trigonometric functions are defined in terms of a point on a terminal side r is found by using the Pythagorean Theorem: 22 yxr
  • 5. RELATION BETWEEN DEGREE AND RADIUS 1 radian= 180属/ =57属16 1属 = /180 radian
  • 6. THE 6 TRIGONOMETRIC FUNCTIONS OF ANGLE ARE: sin y r cos tan , sin 0 0 0 csc , sec , cot , r y y r x x x y y 0x
  • 7. THE TRIGONOMETRIC FUNCTIONS The trigonometric values do not depend on the selected point the ratios will be the same:
  • 8. First Quadrant: sin = + cos = + tan = + cosec = + sec = + cot = +
  • 10. y x
  • 11. y x
  • 12. ALL STAR TRIG CLASS Use the phrase All Star Trig Class to remember the signs of the trig functions in different quadrants: AllStar Trig Class All functions are positive Sine is positive Tan is positive Cos is positive
  • 13. The value of any trig function of an angle is equal to the value of the corresponding trigonometric function of its reference angle, except possibly for the sign. The sign depends on the quadrant that is in. So, now we know the signs of the trig functions, but what about their values?...
  • 14. REFERENCE ANGLES The reference angle, 留, is the angle between the terminal side and the nearest x-axis:
  • 15. ALL STAR TRIG CLASS Use the phrase All Star Trig Class to remember the signs of the trig functions in different quadrants: AllStar Trig Class All functions are positive Sine is positive Tan is positive Cos is positive
  • 16. TRIGONOMETRIC IDENTITIES Reciprocal Identities 1 sin csc x x 1 cos sec x x 1 tan cot x x sin tan cos x x x cos cot sin x x x Quotient Identities
  • 17. QUADRATIC ANGLES (TERMINAL SIDE LIES ALONG AN AXIS)
  • 18. THE VALUE OF TRIGONOMETRIC FUNCTIONS FOR SOME COMMON ANGLES. 0 /6 /4 /3 /2 3/2 2 0 遜 1/ 2 3 /2 1 0 -1 0 1 3 /2 1/ 2 遜 0 -1 0 1 0 1/ 3 1 3 Not defined 0 Not defined 0 sin cos tan
  • 19. TRIGONOMETRIC IDENTITIES 2 2 1sin cosx x 2 2 1 cot cscx x 2 2 1tan secx x Pythagorean Identities The fundamental Pythagorean identity: Divide the first by sin2x : Divide the first by cos2x :