\(Let\ tan\ x = t\)
\(∴ sec^2x\ dx = dt\)
\(⇒ ∫\frac {sec^2x}{\sqrt {tan^2 x+4}}\ dx = ∫\frac {dt}{\sqrt {t^2+2^2}}\)
\(=log\ |t+\sqrt {t^2+4}|+C\)
\(=log\ |tan x+\sqrt {tan^2 x+4}|+C\)
Let \( f : (0, \infty) \to \mathbb{R} \) be a twice differentiable function. If for some \( a \neq 0 \), } \[ \int_0^a f(x) \, dx = f(a), \quad f(1) = 1, \quad f(16) = \frac{1}{8}, \quad \text{then } 16 - f^{-1}\left( \frac{1}{16} \right) \text{ is equal to:}\]

There are many important integration formulas which are applied to integrate many other standard integrals. In this article, we will take a look at the integrals of these particular functions and see how they are used in several other standard integrals.
These are tabulated below along with the meaning of each part.
