Let's find the inflection points, we'll need to solve the equation for this
$$\frac{d^{2}}{d x^{2}} f{\left(x \right)} = 0$$
(the second derivative equals zero),
the roots of this equation will be the inflection points for the specified function graph:
$$\frac{d^{2}}{d x^{2}} f{\left(x \right)} = $$
the second derivative$$\frac{2 \sqrt{x} \left(\frac{\tan^{2}{\left(x \right)} + 1}{\tan^{2}{\left(x \right)}} - 1\right) \left(\tan^{2}{\left(x \right)} + 1\right) - \frac{\tan^{2}{\left(x \right)} + 1}{\sqrt{x} \tan{\left(x \right)}} - \frac{1}{4 x^{\frac{3}{2}}}}{\tan{\left(x \right)}} = 0$$
Solve this equationThe roots of this equation
$$x_{1} = 23.5407035002745$$
$$x_{2} = -86.3880101011813$$
$$x_{3} = -58.1108597415507$$
$$x_{4} = 17.2497696527847$$
$$x_{5} = 36.1144702082836$$
$$x_{6} = 98.9551157707129$$
$$x_{7} = -17.2497696527847$$
$$x_{8} = 86.3880101011813$$
$$x_{9} = -83.2461990037822$$
$$x_{10} = -36.1144702082836$$
$$x_{11} = -42.39970801623$$
$$x_{12} = 39.2571712992709$$
$$x_{13} = 67.5368386175974$$
$$x_{14} = 1.11791403207435$$
$$x_{15} = -7.7897512567741$$
$$x_{16} = 32.9715576965888$$
$$x_{17} = 92.6715878578012$$
$$x_{18} = -89.5298058659662$$
$$x_{19} = 14.101702831878$$
$$x_{20} = 76.9625232987661$$
$$x_{21} = 26.6847992011637$$
$$x_{22} = -67.5368386175974$$
$$x_{23} = 70.6787603857481$$
$$x_{24} = -64.3948847286922$$
$$x_{25} = 80.104370769356$$
$$x_{26} = -70.6787603857481$$
$$x_{27} = -51.8266310849037$$
$$x_{28} = -14.101702831878$$
$$x_{29} = -48.6844157231755$$
$$x_{30} = 61.2528937747202$$
$$x_{31} = -98.9551157707129$$
$$x_{32} = 64.3948847286922$$
$$x_{33} = 58.1108597415507$$
$$x_{34} = 54.9687752392829$$
$$x_{35} = -32.9715576965888$$
$$x_{36} = -39.2571712992709$$
$$x_{37} = -23.5407035002745$$
$$x_{38} = -95.8133574317394$$
$$x_{39} = 89.5298058659662$$
$$x_{40} = 10.949895994345$$
$$x_{41} = -92.6715878578012$$
$$x_{42} = -20.3958349886934$$
$$x_{43} = 95.8133574317394$$
$$x_{44} = 29.8283668577611$$
$$x_{45} = 20.3958349886934$$
$$x_{46} = 7.7897512567741$$
$$x_{47} = -29.8283668577611$$
$$x_{48} = -73.8206541354127$$
$$x_{49} = 42.39970801623$$
$$x_{50} = 45.5421144075225$$
$$x_{51} = -76.9625232987661$$
$$x_{52} = -1.11791403207435$$
$$x_{53} = 4.60357245433596$$
$$x_{54} = -4.60357245433596$$
$$x_{55} = -26.6847992011637$$
$$x_{56} = 83.2461990037822$$
$$x_{57} = 51.8266310849037$$
$$x_{58} = -80.104370769356$$
$$x_{59} = -54.9687752392829$$
$$x_{60} = 73.8206541354127$$
$$x_{61} = 48.6844157231755$$
$$x_{62} = -45.5421144075225$$
$$x_{63} = -10.949895994345$$
$$x_{64} = -61.2528937747202$$
You also need to calculate the limits of y '' for arguments seeking to indeterminate points of a function:
Points where there is an indetermination:
$$x_{1} = 0$$
$$\lim_{x \to 0^-}\left(\frac{2 \sqrt{x} \left(\frac{\tan^{2}{\left(x \right)} + 1}{\tan^{2}{\left(x \right)}} - 1\right) \left(\tan^{2}{\left(x \right)} + 1\right) - \frac{\tan^{2}{\left(x \right)} + 1}{\sqrt{x} \tan{\left(x \right)}} - \frac{1}{4 x^{\frac{3}{2}}}}{\tan{\left(x \right)}}\right) = - \infty i$$
$$\lim_{x \to 0^+}\left(\frac{2 \sqrt{x} \left(\frac{\tan^{2}{\left(x \right)} + 1}{\tan^{2}{\left(x \right)}} - 1\right) \left(\tan^{2}{\left(x \right)} + 1\right) - \frac{\tan^{2}{\left(x \right)} + 1}{\sqrt{x} \tan{\left(x \right)}} - \frac{1}{4 x^{\frac{3}{2}}}}{\tan{\left(x \right)}}\right) = \infty$$
- the limits are not equal, so
$$x_{1} = 0$$
- is an inflection point
Сonvexity and concavity intervals:Let’s find the intervals where the function is convex or concave, for this look at the behaviour of the function at the inflection points:
Concave at the intervals
$$\left(-\infty, 1.11791403207435\right]$$
Convex at the intervals
$$\left[98.9551157707129, \infty\right)$$