Given that cosΘ = 1/2 and that Θ lies in quadrant IV, determine the value of tanΘ.

Question

anonymous · Answer

find $\sin(\theta)$ then tangent is sine over cosine

anonymous · Answer

how do I find sinΘ?

anonymous · Answer

you can find that point on the last page of this cheat sheet
look in quadrant IV where the first coordinate is $\frac{1}{2}$ and the sine will be the second coordinate
there are other ways to do it, but it is easy to see on the sheet

anonymous · Answer

the other way is to compute $$-\sqrt{1-\left(\frac{1}{2}\right)^2}$$

dayakar · Answer

|dw:1460601363058:dw|

anonymous · Answer

-√(1+(1/2)^2) = -√5/2

anonymous · Answer

minus, not plus

anonymous · Answer

$$\huge -\sqrt{1\color{red}-\left(\frac{1}{2}\right)^2}$$

dayakar · Answer

AB^2 = OB^2 - OA^2
          = 2^2 - 1^2


            = 4-1
             =3
$$AB=-\sqrt{3}$$

anonymous · Answer

unit circle cheat sheet is very helpful here

dayakar · Answer

$$TAN \theta = \frac{ AB }{ OA }$$

anonymous · Answer

Thanks!