SOLUTION: Given that cos x = 3/5 and sin x is positive. What is sin (x -pi), cos (x- pi), sin (x), sin (x- pi/2), cos (x-pi/2)? I believe sin (x) is 4/5 and sin (x-pi/2) is -3/5

Question 1053819: Given that cos x = 3/5 and sin x is positive.
What is sin (x -pi), cos (x- pi), sin (x), sin (x- pi/2), cos (x-pi/2)?
I believe sin (x) is 4/5 and sin (x-pi/2) is -3/5

Answer by rothauserc(4718) (Show Source): You can put this solution on YOUR website!
The model for this is a 3-4-5 right triangle
:
We find cos^(-1) of 3/5, this is the inverse cos of (3/5) to find degrees of x
:
The angle opposite the side 3 is 36.86 degrees and angle opposite side 4 is 53.13 degrees
:
Note that angle x is 53.13 degrees
:
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sin(53.13) = 0.7999 approx 0.80 = 4/5
:
sin(53.13-(180/2)) = -6.0000 = -3/5
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