ANSWER
C. sin 126°
EXPLANATION
-576° is coterminal with ±216,±144.
Therefore
cos (-576°)=cos(±216°)=cos(±144°)
The principal angle for -576° is 36° .
Since the terminal side of -576° is in the second quadrant and the cosine ratio is negative in the second quadrant,
cos (-576°)=-cos (±36°)
Also from complementary angles
cos (-576°)=-cos (36°)=-sin (90-36)=-sin(54°)
