### Video Transcript

Find sin π, given π is in standard position and its terminal side passes through the point three-fifths, negative four-fifths.

So we have this π₯, π¦-point. And if we were to plot this on a graph, π₯ is positive and π¦ is negative, so we would be in quadrant four. So again, we would be in quadrant four.

The quadrants start in the upper right-hand corner, and it goes counterclockwise. And it says that the terminal side passes through this point. So when we create an angle, we start at the initial side thatβs at zero degrees, and we keep going around counterclockwise until we get to our terminal side.

And it says this terminal side goes through the point three-fifths, negative four-fifths, so letβs think about these π₯, π¦-coordinates for a minute. The π₯-coordinate of the point where the terminal side of an angle measuring π in standard position which is what we have in a rectangular corner system intersects the unit circle is cos π, and the π¦-coordinate is sin π.

And since itβs asking for sin π, we know that itβs equal to negative four-fifths. Therefore, sin of π is equal to negative four-fifths.