SOLUTION: what is sin630? Technically, it's on the 270 degree line (between 3rd & 4th quadrant) Since it's on the y-intercept, wouldn't that made the triangle undefined? I'm not too

Algebra ->  Trigonometry-basics -> SOLUTION: what is sin630? Technically, it's on the 270 degree line (between 3rd & 4th quadrant) Since it's on the y-intercept, wouldn't that made the triangle undefined? I'm not too      Log On


   

Question 791551: what is sin630?
Technically, it's on the 270 degree line (between 3rd & 4th quadrant)
Since it's on the y-intercept, wouldn't that made the triangle undefined?
I'm not too sure how this works, Please reply ASAP. Thank you.
Found 2 solutions by jim_thompson5910, KMST:
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
Since sin(270) = -1, this means that sin(630) = -1

The reason why sin(270) = -1 is because sin(theta) is equal to the y coordinate of the point on the unit circle. It turns out that the y coordinate at this angle is -1.

Answer by KMST(5347) About Me  (Show Source):
You can put this solution on YOUR website!
Trigonometric functions cosine and sine are defined as the x and y coordinates of the point where the second side of the angle intersect the unit circle (a circle of radius 1, centered at the origin).
The angles are placed on the standard position of the first side coinciding with the positive x-axis, and angles are measured as the counterclockwise turn from the first side to the final side.
If you turn the positive x-axis counterclockwise 1%263%2F4 turns, that is a 360%5Eo%287%2F4%29=630%5Eo.
After that turn, the final side of the angle overlaps the negative y-axis, and intersects the unit circle at the point (0,-1), with x=0, y=-1, so cos%28630%5Eo%29=0 and sin%28630%5Eo%29=-1.