limit x->0 tan(x)/x
Compute the limit of tan(x)x as x0
The limit of tan(x) is 0 when x0
For tan(x)x, the limit takes the indeterminate form 0/0 when x0
We look for a Taylor expansion of the expression: tan(x)
Apply the Taylor development tan(A) + (1 + tan(A)2)·(X -A) of tan with X=x around A=0 (order N=1)
tan(0) + (1 + tan(0)2)·(x + 0)
0 + (1 + 02)·x
Let's restart using the Taylor expansion: x
xx
1
So the limit of tan(x)x is 1 when x0
Answer:   1