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anonymous
 4 years ago
Suppose θ is in the interval (180°, 225°). Find the sign of each function value.
a) Cos(2θ)
b) tan(θ90°)
c) sin(θ/2)
anonymous
 4 years ago
Suppose θ is in the interval (180°, 225°). Find the sign of each function value. a) Cos(2θ) b) tan(θ90°) c) sin(θ/2)

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dumbcow
 4 years ago
Best ResponseYou've already chosen the best response.0a) 2A puts you in 1st quadrant > cos(2A) is positive b) A90 puts you in 2nd quadrant > tan(A90) is negative c) A/2 puts you in 2nd quadrant > sin(A/2) is positive

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0How do you get to that? Is there any mathmatics behind it that will help me associate it so I can repeat this?

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0this (rough) diagram should help\ dw:1328624954731:dw

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0so in first quadrant (090) all trig ratios are positive in 2nd (90180) sine is pos. cos and tan are neg. in 3rd (180270) tan is pos. sin and cos are neg. in 4th (270360) cos is pos. sin and tan are neg.

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0also as an aid to memory you can memorise CAST  'Cos  All  Sin  Tan' these are the ratios which are positive in the quadrants : dw:1328625567936:dw eg 250 degrees  is in third quadrant : the tangent is positive, cos and sine are negative

anonymous
 4 years ago
Best ResponseYou've already chosen the best response.0Yes this is great information. However, I still don't understand how you find: Suppose θ is in the interval (180°, 225°). Find the sign of each function value. a) Cos(2θ) : What would this be Cos(2*180)? b) tan(θ90°) c) sin(θ/2)
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