Find the point on the terminal side of θ = -3pi/4 that has an x coordinate of -1.

Question

Find the point on the terminal side of θ = -3pi/4  that has an x coordinate of -1.

anonymous · Answer

terminal side of what ??

anonymous · Answer

I assume the equation itself.

tkhunny · Answer

Okay, so $(-1,Something)$ is at $-3\pi/4$.

1) Where is $-3\pi/4$?  What quadrant is it in?
2) What is the reference angle there?
3) You've a Pythagorean theorem to help you the rest of the way.

anonymous · Answer

It's in the second quadrant. 
Reference angle?

tkhunny · Answer

Are you sure you have the background to solve this problem?

It's in the 3rd quadrant.  $+3\pi/4$ is in the 2nd quadrant.

It is not encouraging that you don't know what a reference angle is.  You will need that information.  Draw a ray from the origin in the direction of $\3\pi/4$.  What angle does this ray make with the x-axis?

anonymous · Answer

Gotcha because it is negative. Well below the 3pi/4 is 225 degrees? This is from the unit circle.

tkhunny · Answer

@tanjeetsarkar96 Are you just guessing?  You had it right before, but please do not just post answers.

tkhunny · Answer

Kind of.  It's really -135º, but this gest you to the same place as +225º.  Good work.  Now the reference angle.

anonymous · Answer

Well the answer does make since now that I think about it. Since the unit circle is only 1 digit  for the x axis and the y axis, going to the very edge would force the y corrdinate to be 0. Is this the correct reasoning?

anonymous · Answer

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