find the exact value of the expressions WITHOUT a calculator?

Question

c) sin[cos^-1(-(sq root 3)/2)]


d) cos^-1[cos(2pi/3)]


e) cos[sin^-1(1/2)]

Answer 1

c) sin[cos^-1(-(sq root 3)/2)] = sin(5pi/6) = 1/2

d) cos^-1[cos(2pi/3)] = 2pi/3

e) cos[sin^-1(1/2)] = cos(pi/6) = (sq root 3)/2
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To the answer below me,
Thank you.

Answer 2

sin(5pi/6) = 1/2 not -1/2
Everthing else that Sahsjing answered looks okay.