Trigonometric Ratios Worksheet Page 4

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1.2  Sine, Cosine, and Tangent of Angles from 0
 to 360
°
°
KEY CONCEPTS
•  For any rotation angle  in standard position that has  
y
a point P(x, y) on its terminal arm, the primary  
P(x, y)
y
__
r     ,   
trigonometric ratios for the angle are sin  =    
 
_______
y
x
__
__
r    ,  and tan  =    
x     ,  where r =  
√  
      .
2
    +   y  
2
r
cos  =    
 
 
  x  
•  Pairs of related angles can be found using the  
x
0
coordinates of the endpoints of their terminal arms  
and a reference angle in quadrant I.
Example
The coordinates of a point on the terminal arm of an angle  in standard position are  
G(−3, −5). Determine the exact primary trigonometric ratios for .
Solution
Plot G(−3, −5) on a coordinate grid. 
y
6
4
2
�3
x
0
2
4
6
�6
�4
�2
�2
�5
r
�4
Determine r.
G(�3, �5)
�6
_______
√  
  x  
2
    +   y  
2
     
r =  
_____________
√  
  ( −3) 
2
    +   ( −5) 
2
r =  
     
___
r =  
√  
3   
y
y
x
__
__
__
sin  =    
r        
 
cos  =    
r     
 
tan  =    
x    
 
−5
−3
−5
____  
____
___
___
   =    
___
=    
=    
     
     
   
−3
√  
3   
√  
3   
5
3
5
____
____
__
= −   
___
= −   
___
=    
     
     
   
3
√  
3   
√  
3   
  MHR  •  Chapter 1  978-0-07-090893-2
  Printer Pdf

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