sin270,

tan x > sin x > cos x 由225 0(d点)至 270 0 , tan x > cos x > sin
sin1/x图像是怎样的?
tαnα=0 cotα→∞ secα=-1 cscα→∞ α=270°(3π/2) sinα=-1
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acta pharmacol sin. 2020 feb;41(2):270-277.