If the angle is in standard position and P(x, y) is a point on the terminal side of , and r is the distance from the origin to P, then sin() = Incorrect: Your answer is incorrect. cos() = tan() = .

cos(a) = x/r

sin(a) = y/r

tan(a) =  y/x

In the image at the end, you can see a sketch of the situation, we can model this with a triangle rectangle:

The hypotenuse length is equal to r, the adjacent cathetus to the angle is the x-value, and the opposite cathetus to the angle is the y-value.

Now we can remember the trigonometric relations:

cos(a) = (adjacent cathetus)/(hypotenuse)

sin(a) = (opposite cathetus)/(hypotenuse)

tan(a) = (opposite cathetus)/(adjacent cathetus)

Using what we wrote above, we can rewrite these as:

cos(a) = (adjacent cathetus)/(hypotenuse) = x/r

sin(a) = (opposite cathetus)/(hypotenuse) = y/r

tan(a) = (opposite cathetus)/(adjacent cathetus) = y/x

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