Right Triangle Trig (SOH CAH TOA)

The unit circle has radius 1 — neat, but the real world's triangles have sides of 3, 7, 12, anything. Here's the beautiful part: scaling a triangle doesn't change its ratios. So the sin/cos/tan you built on the circle unlock EVERY right triangle, no matter the size. The mnemonic that packs it all: SOH CAH TOA.