Page 6 - Trigonometry
P. 6
Example 1:
When you have trigonometric expressions of the kind,
α sin( ) + cos( ) 1
Then it’s possible to write it as
α sin( ) + cos( ) = cos( − ) 2
This comes from the identity,
cos( − ) = cos( ) cos( ) + sin( ) sin( )
When the right hand side of Eq:2 is expanded,
cos( − ) = cos( ) cos( ) + sin( ) sin( )
= [ sin( )] sin( ) + [ cos( )] cos( )
Compare with Eq:1,
= sin( ) and = cos( ) 3
When these are divided,
tan( ) = and γ = tan −1 ( ) 4
When you square and add,
2
2
= √ + 5
2
