I believe 60 degree is your answer
Semi monthly means 2 times per month
assume that pay is at beginning and middle of month (doesn't matter, but makes it easier for me)
so 12 months
2 times per month
12 times 2=24
divide 55000 by number of months
55,000/24=2291.67
so the amount per paycheck, assuming equally distributed amounts throughout the paychecks, is $2291.67
Tangent always meets radius at 90° angle.
Angle ABC = 90° so Pythagoras' theorem applies.
r² + 4² = (r+2)²
r² + 16 = r² + 4r + 4
12 = 4r
r = 3