Question 1103528
if tan theta=10/7, and if cos theta <0 then
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tan + and cos minus --> Q4 --> x is +, y is negative
y = 10
x = -7
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tan = y/x
r = sqrt(x^2+y^2) = sqrt(149)
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cos theta= y/r = -10/sqrt(149)
sec theta= 1/cos = -sqrt(149)/10
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sin theta= sqrt(1 = cos^2)  --- positive in Q4
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tan theta/2= sin/cos
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sin 2theta= 2sin*cos
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sin theta/2= --- Look up "Half Angle formulas" on Wikipedia.