THERE ARE EIGHT FUNDAMENTAL TRIGONOMETRIC IDENTITIES WHICH ARE BASIC TO PROVING OTHER TRIG RELATIONSHIPS.

THEY ARE:

THE RECIPROCAL IDENTITIES
RECIPROCAL IDENTITIES EQUATION

 

THE QUOTIENT IDENTITIES
QUOTIENT IDENTITIES EQUATION

 

THE PYTHAGOREAN IDENTITIES
PYTHAGOREAN IDENTITIES EQUATION

 


EXAMPLE 1

GIVEN SIN X = 0.7986 AND COS X = 0.6018, FIND TAN X WITHOUT THE AID OF THE TRIG FUNCTION ON YOUR CALCULATOR.


EXAMPLE 2


EXAMPLE 3

 


THE FOLLOWING EXAMPLES INVOLVE PROOF. THIS IS WHERE MOST STUDENTS ENCOUNTER DIFFICULTY SO THERE ARE A LOT OF EXAMPLES TO ASSIST YOU .

KEEP IN MIND THE PURPOSE OF A PROOF IS TO GET THE LEFT SIDE = RIGHT SIDE.

USE THE EIGHT FUNDAMENTAL IDENTITIES TO COMPLETE THE FOLLOWING PROOFS.

 

EXAMPLE 4

 


EXAMPLE 5


EXAMPLE 6

 


EXAMPLES 7

 


EXAMPLE 8