Question 545976
The exact value of 6cos(-61pi/6)-2sin(13pi/4) is... 
A. 3squaroot(3)+squaroot(2) 
B. -3+squaroot(2) 
C. -3-squaroot(2) 
D. 3squaroot(3)-squaroot(2)
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For(-61π/6), use reference angle(-π/6) in quadrant IV where cos>0
6cos(-61π/6)=6cos(-π/6)=6√3/2=3√3
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For(13&#960;/4), use reference angle(5&#960;/4) in quadrant III where sin<0
2sin(13pi/4)=2sin(5&#960;/4)=2&#8730;2/2=&#8730;2
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6cos(-61pi/6)-2sin(13pi/4)=3&#8730;3-&#8730;2 (ans. D)