SOLUTION: Use the following to find the exact value of sin(theta/2) cos theta= -4/5, theta is in Quadrant 3.

Algebra ->  Trigonometry-basics -> SOLUTION: Use the following to find the exact value of sin(theta/2) cos theta= -4/5, theta is in Quadrant 3.      Log On


   

Question 773346: Use the following to find the exact value of sin(theta/2)
cos theta= -4/5, theta is in Quadrant 3.
Answer by lwsshak3(11628) About Me  (Show Source):
You can put this solution on YOUR website!
Use the following to find the exact value of sin(theta/2)
cos theta= -4/5, theta is in Quadrant 3.
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use x for theta:

check with calculator:
cosx=-4/5 (in Q3)
x=≈36.87º+180º≈216.87º
x/2≈108.43º
sin(x/2)≈sin(108.43º)≈0.9487
Exact value=3/√10≈0.9487