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# Trigonometry

1. find the value of cot(1/2x + pi/6) = -2.5 between 0<x<2 pi

new interval pi/6 < 1/2x + pi/6 < 7/6 pi

1/tanx = -2.5
tanx=-2/5
tan^-1(-2/5) = -0.381
1/2x+ pi/6 = -0.381,3.52
x=-8.66, 5.997

is this correct
2. I would rather use a substitution, y=0.5x +pi/6,
tan y =-5/2
and then go from there
3. y=-1.19,1.951,5.093
0.5x+pi/6=the same
0.5x=1.427,4.569
x=2.85 rad (its the only value I get inside the limit given)

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Updated: October 9, 2016
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