Happy Indigenous Peoples' Day! You can also feel free to celebrate some Italian guy paid by Spain to attempt and fail to get to India, if that's what you're into. Here's the Problem of the Week, which has to do with neither of them.
While you might at first jump to analyzing this as an optimization problem in the style of calculus, you can actually do it wholly geometrically, as I've done it below:
Did you solve the problem the way I did, or another way? Tell us how you did it in the comments!