Question 238122: PLEASE HELP ME SOLVE THIS TRIGONOMETRIC FUNCTIONS:
Name the quadrant in which sin(theta)<0 and cos(theta)<0.
a)l
b)ll
c)lll
d)lV
Answer by Theo(13342)   (Show Source):
You can put this solution on YOUR website! in the first quadrant, the sine and the cosine are both positive.
in the second quadrant, the sine is positive and the cosine is negative.
in the third quadrant, the sine is negative and the cosine is negative.
in the fourth quadrant, the sine is negative and the cosine is poitive.
looks like your answer is the third quadrant.
to prove it to yourself, use your calculator.
take an angle in each quadrant and solve for the sine and the cosine.
example:
go to the first quadrant and pick an angle.
sin(45) = +
sin(45) = +
add 90 degrees to get you into the second quadrant.
sin(135) = +
cos(135) = -
add 90 degrees to get you into the third quadrant.
sin(225) = -
cos(225) = -
add 90 degrees to get you into the fourth quadrant.
sin(315) = -
cos(315) = +
these should conform to what I told you up top.
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