008A Sample Final A, Question 17

From Math Wiki
Jump to navigation Jump to search

Question: Compute the following trig ratios: a)       b)       c)

1) How is secant related to either sine or cosine?
2) What quadrant is each angle in? What is the reference angle for each? Answer:
2) a) Quadrant 2, b) Quadrant 4, c) Quadrant 3. The reference angles are: , and 60 degrees or


Final Answer A:  
Since , and the angle is in quadrant 2,
Final Answer B:  
The reference angle is and is in the fourth quadrant. So tangent will be negative. Since the angle is 30 degees, using the 30-60-90 right triangle, we can conclude that
Final Answer C:  
Sin(-120) = - sin(120). So you can either compute sin(120) or sin(-120) = sin(240). Since the reference angle is 60 degrees, or  , So  

Return to Sample Exam