What is the relationship between arctanx and SiNx and cosx

What is the relationship between arctanx and SiNx and cosx

Arctanx = arctan (Sina / COSA) where x is Sina / cosa (a value) and a is an angle

lim(arctanx/sinx)
x－>0

Using the Equivalent Infinitesimal Substitution, because when X - > 0, arctanx ~ x, SiNx ~ x,
So LIM0 > arctanx / SiNx = LIM0 > x / x = 1

LIM (x-0) arctanx ^ 2 / SiNx / 2arcsinx limit, please write the detailed process

When x tends to zero, arctanx, arcsinx and SiNx are equivalent,
They are all equivalent to X,
So here arctanx ^ 2 is equivalent to x ^ 2, SiNx / 2 is equivalent to X / 2, arcsinx is equivalent to X
that
Original limit
=lim(x->0) x^2 / (x/2 *x)
=2