## marasofia1616 3 years ago Find the point on the terminal side of θ =3pie/4 that has a y coordinate of 1. Show your work for full credit.

1. tjones89

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2. tjones89

the goal is to find the coordinates of the point at the end of that angle. We are told that y = 1 at that point so we just need to find the x coordinate and we're set

3. tjones89

to do this we use the triangle that is made when you draw a line straight down from the point like I have in the drawing

4. tjones89

we know the length of that side is one because we were told that y = 1

5. tjones89

now if we knew the angle inside that triangle we could use the tangent function to find the length of the adjacent side, which I labelled x.

6. tjones89

any idea how we can find it?

7. marasofia1616

tan 3pi/4=1/x?

8. tjones89

nope, you used the wrong angle, we need to find the angle inside that triangle

9. tjones89

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10. tjones89

the 3pi / 4 is outside the triangle

11. marasofia1616

If I use the Unit Circle and says that 3pi/4 is 135... and I am looking for that inside angle I get that it is equal to 45.

12. tjones89

right, so now we can use tangent to find x $\tan(45) = \frac{ 1 }{ x }$

13. tjones89

isolate x and you've got it

14. marasofia1616

x=-1?

15. tjones89

yep!

16. marasofia1616

got it... thanks!

17. lbouskila

how is x= -1?

18. AG1997

So the point would be (-1, 1)?

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