Cot inverse 1 by root 3 value July 8, 2019 16 32 64 128 Cos inverse 1 by root 3 value Cot inverse minus 1 by root 3 value Cos 1 cos 2 cos 3 Cosa=1 3 cos(a+b)=-1 3 求a b∈(0 p 2)求cos(a-b)
