I want proof of the following

lim       sinx/x  =1
x-->0

d/dx (sin x)=cos x

d/dx (cos x)=-sinx

for 1st one ,
u can use l'hosiptal rules or just expand sin x as x- x^3/3! + x^5 /5! ....

for 2nd and 3rd ,
just use first principle of derivative

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