Question

ACT Question: If the value, to the nearest thousandth, of cos theta is -0.385, which of the following could be true about theta?
a.) theta is greater than or equal to 0 and less than pi/6
b.) theta is greater than or equal to pi/6 and less than pi/3
c.) theta is greater than or equal to pi/3 and less than pi/2
d.) theta is greater than or equal to pi/2 and less than 2pi/3
e.) theta is greater than or equal to 2pi/3 and less than or equal to pi

Answer 1

If the cosine of an angle is negative, then the angle is in either the second or third quadrant.

Answer 2

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Answer 3

Mass tag much? There is already someone helping.

Answer 4

Please explain it cause I know the answer from the back of the act book but I just dont get it

Answer 5

Im not helping. @SithsAndGiggles is already helping you why not try to understand them rather than bring attention to the post.

Answer 6

In terms of \(x,y,z\), you have \(\cos\theta=\dfrac{x}{z}\) (where \(\theta\) is the angle I mistakenly left out).

\(z\) is always taken to be a positive number, so if the trig ratio is negative, either \(x\) or \(y\) must be negative.