+1995 Given sin(−θ)=−1/4 and tanθ =√15 / 15
What is the value of cosθ ?
A) −√15 / 4
B) −√15 / 60
C) √15 / 4
D) √15 / 60
+129852 Note.... sin (-θ) = -sin(θ)
And tanθ =√15 / 15 = 1 / √15
So
-sin (θ) = -1/4 ⇒ sin (θ) = 1/4
And
tan (θ) = sin (θ) / cos(θ) rearrange as
cos (θ) = sin (θ) / tan (θ) = (1/4) / (1/ √15) = (1/4) * (√15 / 1) = √15 / 4 ⇒ C
+1995 Much more easier then I anticipated. I was thinking it was that one but I found it more diffuclt but seeing the steps you used which are more simple . Thank you 
+129852 Thanks....sometimes it helps to "un-rationalize" the denominator on those square root ratios ....[if that's even a word.....LOL!!!! ]
+2446 I guess you could consider it to be a rationalization of the numerator.
