## vera_ewing one year ago Math question

1. vera_ewing

2. anonymous

definitely not C

3. anonymous

if you do not have this memorized, do the same as before draw a triangle, find the missing side

4. just_one_last_goodbye

Would love to help but this type of problems are way above my knowledge xD good luck but you got pros that are helping c;' @satellite73 and @phi

5. anonymous

what you need is a good unit circle cheat sheet

6. phi

First step, identify the "line" that represents pi radians (or 180 degrees) ditto for 3pi/2 (270 degrees)

7. vera_ewing

Well I know tanθ = (sqrt)3 , so how do I find cosθ using the triangle?

8. anonymous

look in quadrant 3 to see where the second coordinate is $$-\frac{\sqrt{3}}{2}$$

9. anonymous

you will see that the first coordinate is $$-\frac{1}{2}$$ , that is the cosine

10. vera_ewing

Wait wouldn't it be 1/2 not -1/2 ? Since it's in Quadrant 3?

11. anonymous

you will also see that the angle is $$\frac{4\pi}{3}$$ although you were not asked for that

12. anonymous

no you are below the x axis in quadrant 3, so the first coordinate is negative, as is the second

13. phi

|dw:1436191312914:dw|

14. vera_ewing

Ohhh okay that makes so much more sense! Thank you :)

15. anonymous

just like ordinary graph paper left is negative in the x, down is negative in the y

16. phi

always put in a triangle in the correct quadrant. label the hypotenuse length 1 if they give you the sin, that is the y value if they give you the cos, that is the x value use pythagoras to find the unknown side. or , memorize the angles (painful, but doable)