State an equivalent expression for sin (-7pi/6) in terms of the related acute angle.
I don't really know how to solve these kind of questions, I find everything I google doesn't explain how to do it
State an equivalent expression for sin (-7pi/6) in terms of the related acute angle.
I don't really know how to solve these kind of questions, I find everything I google doesn't explain how to do it
OK , try to follow here . I will go slow .
$\displaystyle \sin (-210)=-\sin 210$ (Step 1)
$\displaystyle -\sin 210=-(-\sin 30)$ (Step 2)
This is because sin is negative in the 3rd quadrant .
$\displaystyle -(-\sin 30)=\sin 30$ (Step 3)
I think this is what the question wants since it asks for acute angles (angle < than 90 degree)
If you still have any problem , just indicate which step you are unsure with .. don say everything or else i don know where to start .
I don't see why degrees should be easier than radians and I think it is good to encourage people to think in terms of radians. $\displaystyle \frac{7\pi}{6}= \pi+ \frac{\pi}{6}$. Since the angle is negative, we swing down from the positive x axis to the negative y axis and then [itex]\pi/6[/itex] above. Now we are in the second quadrant where sine is still postive.
$\displaystyle sin(-\frac{7\pi}{6})= sin(\frac{\pi}{6})$.