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Posted by on Saturday, May 14, 2011 at 11:40am.

If cos 0 = - 1/2 and tan 0 > 0, find the quadrant that contains the terminal side of 0, and then find the exact values of the other five trig functions of 0.

  • trig - , Saturday, May 14, 2011 at 12:09pm

    The cosine is positive in I and IV
    quadrant,negative in II and III quadrant.


    The tangent is positive in I and III guadrant,negative in II and IV quadrant.

    If cos(theta)<0 cosine is negative
    If tan(theta)>0 tangent is positive

    Only quadrant where cosine is nagative,and tangent is positive is quadrant III.

    sin(theta)= + OR - sqroot[1-cos^2(theta)]

    In quadrant III sine is negative so:

    sin(theta)= - sqroot[1-cos^2(theta)]

    sin(theta)= - sqroot[1-(-1/2)^2]

    sin(theta)= - sqroot(1-1/4)

    sin(theta)= - sqroot(3/4)

    sin(theta)= - sqroot(3) /2

    tan(theta)=sin(theta)/cos(theta)=
    [-sqroot(3)/2]/(-1/2)= + sqroot(3)=
    sqroot(3)

    ctg(theta)=1/tan(theta)=1/sqroot(3)

    sec(theta)=1/cos(theta)=1/(-1/2)= -2

    cosec(theta)=1/sin(theta)=1/[-sqroot(3) /2]= -2/sqroot(3)

  • trig - , Tuesday, October 4, 2011 at 10:23pm

    determine all trig functions of theta using the given info, state the answers correct to the nearest hundredth.
    cos (theta) = -5/13; tan (theta) < 0

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