So it has radius one, unit circle. So what does the length of this salmon colored line represent? Well, the height of this line would be the y coordinate of where this radius intersects the unit circle. And so by definition, by the unit circle definition of trig functions, the length of this line is going to be sine of theta. If we wanted to make sure that it also worked for thetas that end up in the fourth quadrant, that will be useful, we can just ensure that it's the absolute value of the sine of theta. Now what about this blue line over here? Can I express that in terms of a trigonometric function?