/sci/ - Science & Math

>>14836918
Sin of angle is defined as the y coordinate of the point where a line that makes that angle, intersects a circle centred at the origin with radius 1. Or equivalently, it is the ratio of the y coordinate of any point on a line that makes that angle (like the one you have drawn) to the distance of that point from the origin. You can see that y coordinate for the reference angle is also the same except for the sign.