Question

Pre-Calculus Help?

I've been stuck on this problem for a while, so I was wondering if anyone could help walk me through solving it?

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

Answer 1

This point in the third quadrant.

Answer 2

Think about isosceles triangle

Answer 3

Let O be the origin
Let M=(-1,0) and the N=(1,y) our point
The triangle OMN is a right isosceles triangle.
ON=y=?

Answer 4

Are you with me?

Answer 5

Yeah, I think so, but I'm still not understanding how exactly to find the y coordinate

Answer 6

draw a picture and you can find out how much is y

Answer 7

I did, but I still don't get it. I think it's supposed to be solved with the unit circle somehow

Answer 8

My textbook really sucks at explaining things. This problem is from a lesson based off of trig functions though

Answer 9

I see what you mean, but how do you know for sure that it goes down that far? Is there a way to algebraically explain it?

Answer 10

Wait a second

Answer 11

Ok

Answer 12

You see the arc is the angle - 3pi/4

Answer 13

Yeah I see that

Answer 14

So is the only way to explain it through graphing like that? There's no algebraic way to solve it?

Answer 15

intersect the line coming from the origin to the tip of the arc and the line x=-1, you get your terminal point

Answer 16

This is the easiest way to do it

Answer 17

That is a proof and you can take it to the bank

Answer 18

Trigonometry is bes understood using geometry

Answer 19

For problems like this and others, visit my site
http://saab.org

Answer 20

So there is no algebraic way to solve it? I know that geometry is easier, but I also need to know if there's an algebraic way to solve it

Answer 21

A picture is equal thousand of words. When you can draw a picture, use it.