[tzs]

If you want a hint for the firing squad, start out by limiting the number of participants to powers of two, and think recursively.

If you want a hint for the bicycle problem, think about tangents.

[chmike]

Anyone who drives a bycicle knows that the rear wheel follows a smooth path compared to the front wheel. So this image is easy. I guess there might be more tricky images. A straight line for instance ;)