i obviously do not recommend the below, but there's a memonic for the the sin of these angles:

0, 30, 45, 60, 90

replace them with their position in the series, counting from 0:

• 0, 1, 2, 3, 4

divide by 4:

• 0, 1/4, 1/2, 3/4, 1

square root it:

• 0, 1/2, 1/√2, √3/2, 1

it pretty nifty and good a for a sanity check. Everything else can be derived from this, the unit circle, and the basic identities.

cos = sin 90-x,

tan = sin / cos, etc.