SOLUTION: Use a sum or difference formula to determine the value of the trigonometric function.
cos(7π/4+5π/6)
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-> SOLUTION: Use a sum or difference formula to determine the value of the trigonometric function.
cos(7π/4+5π/6)
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You can put this solution on YOUR website! Use a sum or difference formula to determine the value of the trigonometric function.
cos(7π/4+5π/6)
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cos(s+t)=cos s cos t - sin s sin t
For given function:
s=7π/4
t=5π/6
..
Cos s=cos(7π/4)=cos π/4 in quadrant IV=√2/2
Cos t=cos(5π/6)=cos π/6 in quadrant II=-√3/2
..
sin s=sin(7π/4)=sin π/4 in quadrant IV=-√2/2
sin t=sin(5π/6)=sin π/6 in quadrant II=1/2
..
cos(7π/4+5π/6)
=(√2/2*-√3/2)-(-√2/2*1/2)
=-√6/4-(-√2/4)
=(-√6+√2)/4
Check:
cos(7π/4+5π/6)=cos(315+150)=cos 465º=-.2588
(-√6+√2)/4=-.2588
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