lim x approaching 0, cscx(secx^2-1)
csc(x)*(sec(x)^2 - 1) → tan(x)^2/sin(x) → tan(x)/cos(x)
limit as x→0 csc(x)*(sec(x)^2 - 1) = limit as x→0 tan(x)/cos(x) → 0/1 → 0
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