I'm working on building tetris now in Java and am at the point of rotations...
I originally hardcoded all of the rotations, but found that linear algebra was the better way to go.
I'm trying to use a rotation matrix to rotate my pieces, and found I need a good understanding of trigonometry.
That being said, the way I visualize sin and cos is on the bottom part of the picture... a circle drawn on a graph... but images online show the sin cos relationship as the above picture... two waves that are "90 degrees" away from each other...
So, my questions are:
1) I can't seem to visualize how they are 90 degree apart. I can't see how those angles are formed in the above graph from sin and cos.
2) It's said that the relationship is
Sin X = Cos (90 - x), and that sin is opposite/hypotenuse and cos = adjacent/hypotenuse... but what exactly does that mean? What do the quotients of these mean in relation to an angle? Let's say x = 45 degrees, adjacent = 5 inches, hypotenuse = 5 inches, and opposite = 4 inches... so
sin would be 5"/9" = .55 inches... What does this .55 inches mean in relation to the angle? How is it helpful?