**Important Limits**

Before we go on to the differentiation part, we have to have some knowledge of some important limits, where some of them trivial but some very important.

(A) Zero and Infinity

(B) A mathematical constant

This constant is very useful when it comes to calculus, since the derivative of this base in logarithm is interesting. This constant is similar to pi in many ways, including the fact that it is transcendental.

(C) Trigonometric limits

Let's consider the areas of triangles and the sector.

There is also another important limit in order to prove some derivatives afterwards.

Please note these limits by heart because they will become useful when we proceed.