Jelly, 1010 9 bytes
O%15O:3 ı*SḤA
I fiddled around with other functions to see if I could get rid of the space by finding a different one-byte dyad that would take a two-digit number on the left rather than the right, but it turned out that : doesn't need two digits to produce the desired values.
O Codepoints of the input
:3 floor divided by 3.
ı* Raise sqrt(-1) to the power of each,
S sum,
Ḥ double,
A and take the absolute value.