Question

find the exact value for cosine and sine of 2,1oo degree thanks

Answer 1

I guess that is 2100 degrees. Well, you know
cos or sin of Theta= cos or sin (theta-n*360)

so what is n?
2100/360= 5 and remainder 120 deg

sin2100= sin120 deg
but sin120=sin(180-120)=sin60
cos2100=cos120=-cos(180-120)=-cos60=-sin30

check this.