Consider this example provided by my teacher:

7. Give the exact value of each expression without using a calculator. (a) cos (2 tan-1 4 = 4 tane tan-1 4 = 0 2 tan-1 2 2 COS = cos 20 = cos20 - sin20 = 16 7 25 25 25(c) sin sin-1= + tan-1(3) ) A B = sin(A + B) = sinAcosB + cosAsinB 1+3V3 10 /10+3v30 2v10 V10 20 2 V10 3 A V3 B7. Give the exact value of each expression without using a calculator. (a) cos (2 cos-1 IN (b) sin cos-1 + tan-1(2) )