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Home > Schools
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Notes IX-XII > Notes & Assignments XI
Assingment trignomatric functions
Simple rule to remember:
ALL SCHOOL TO COLLEGE
OR
AFTER SCHOOL TO COLLEGE
OR
ADD SUGAR TO COFFEE

TRIGONOMETRIC RATIOS OF ANGLES (-
)
1. sin(-
) = -sin 
2. cos(-
) = cos 
3. tan(-
) = - tan 
4. cosec(-
) = - cosec 
5. sec(-
) = sec 
6. cot(-
) = - cot 
TRIGNONOMETRIC RATIOS OF 
1. sin
= cos 
2. cosec
= sec 
3. cos
= sin 
4. tan
= cot 
5. sec
= cosec 
6. cot
= tan 
TRIGONOMETRIC RATIOS OR 
1. sin
= cos 
2. cos
= -sin 
3. tan
= - cot 
4. cosec
= sec 
5. sec
= - cosec 
6. cot
= - tan 
TRIGONOMETRIC RATIOS OF 
1. sin
= sin 
2. cos
= - cos 
3. tan
= - tan 
4. cosec
= cosec 
5. sec
= - sec 
6. cot
= - cot 
TRIGONOMETRIC RATIOS OF 
1. sin
= -sin 
2. cos
= - cos 
3. tan
= tan 
4. cosec
= - cosec 
5. sec
= - sec 
6. cot
= tan 
TRIGONOMETRIC RATIOS OF 
1. sin
= - sin 
2. cos =
cos 
3. tan =
- tan 
4. cosec =
- cosec 
5. sec =
sec 
6. cot =
- cot 
TRIGONOMETRIC RATIOS OF 
1. sin =
sin 
2. cos
= cos 
3. tan
= tan 
4. cosec
= cosec 
5. sec
= sec 
6. cot
= cot 
(i) For angle 0-
, -
, +
, 2
-
, 2
+
, the trigonometric ratio remains to be the same.
sin (-
) = - sin
, tan ( +
)
= tan
, cos (2
-
) = cos
(ii) For angles ,
,
,
the trigonometric ratio changes from cos
to sin ,
tan
to cot ,
cosec
to sec
and vice versa.
Example:
sin
= cos 
tan
= cot 
sec
= - cosec
etc.
TRIGONOMETRIC RATIOS OF (x+y)
1. sin(x + y) = sin x cos y + cos x sin y
2. cos (x + y) = cos x coy - sin x sin y
3. tan (x +y) = 
4. cot (x + y) = 
TRIGONOMETRIC RATIOS OF (x- y)
1. sin (x - y) = sin x cos y - cos x sin y
2. cos (x - y) = cos x cos y + sin x sin y
3. tan (x -y) = 
4. cot (x - y) = 
TRIGONOMETRIC RATIOS OF (2x)
1. sin 2x = 2 sin x cos x = 
2. tan 2 x = 
3. cos 2x = cos2 x - sin2 x = 2 cos2 x - 1 =
1 - 2 sin2 x = 
TRIGONOMETRIC RATIOS OF (3 x )
1. sin 3 x = 3 sin x - 4 sin3 x
2. cos 3 x = 4 cos3 x - 3 cos x
3. tan 3 x = 
Sum and Difference of two like ratios:
1. sin x + sin y = 2 sin
cos 
2. sin x - sin y = 2 cos
sin 
3. cos x + cos y = 2 cos
cos 
4. cos x - cos y = - 2 sin
sin 
Product of Trigonometric Ratios:
1. 2 sin x cos y = sin (x + y) + sin (x - y)
2. 2 cos x sin y = sin (x + y) - sin (x - y)
3. 2 cos x cos y = cos (x + y) + cos (x - y)
4. 2 sin x sin y = cos (x - y) - cos (x - y)
General Solution of an Equation
1. If sin
= 0, then
= n ,
n є 
2. If cos
= 0, then
= (2 n + 1) ,
n є 
3. If tan
= 0, then
= n ,
n є 
4. sin
= sin
= n
+ (- 1)n
, n є 
5. cos
= cos
= 2 n
,
n є 
6. tan
= tan
= n
+ ,
n є 
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