Just move your mouse! The radius and angle will change to fit with the mouse's position, and as a result changing the lengths of sine, cosine tangent. Press space to see three more - secant, cosecant and cotangent. They will replace the old ones, press space again to make them come back. It might look like secant is just a random line, but it actually ends where the tangent would cross the x-axis. Click space and you will see that the green tangent line ends at the same place. In other words, it completes the triangle: radius-tangent-secant.
All by me! Only 1 sprite so far! 100% Pen. Can help with remembering identities and triangles. I'm thinking of making a hyperbolic version...but I'll need some more functions for that! "Undefined!" means that the calculation does not make sense - like dividing by 0, getting a negative root...in maths terms, using a function outside it's domain. There are tons of angle theorems, comparisons and identities in this circle. How many can you find?
