Trigonometry

posted by George

Thank you STEVE!!!!!

Suppose that Cos (theta) = 1/square root 2

if 0<equal to theta , pi/2 then
sin(theta) =
tan (theta) =

If 3pi/2 less than equal to theta , 2pi then
sin(theta) =
tan (theta) =

I know the trig functions but I feel like I am missing something here. cos (theta) = adj/hyp sin(theta) = opp/hyp...im getting confused with the numbers I am getting..can you help me solve these?

  1. Steve

    always draw diagrams in the correct quadrants for this kind of stuff.

    You know that if cosθ = 1/√2, θ = 45°, and the triangle has sides 1,1,√2

    So, in QI, x and y are both positive, and
    sinθ = y/r = 1/√2
    tanθ = y/x = 1/1 = 1

    In QIV, x>0 and y<0, so
    sin = y/r = -1/√2
    tan = y/x = -1

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