El gráfico de la función cruce el eje X con f = 0
o sea hay que resolver la ecuación:
$$\tan{\left(\frac{\left(-1\right) 9 x}{5} \right)} = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje X:
Solución analítica$$x_{1} = 0$$
Solución numérica$$x_{1} = 62.8318530717959$$
$$x_{2} = -6.98131700797732$$
$$x_{3} = 73.3038285837618$$
$$x_{4} = 40.1425727958696$$
$$x_{5} = -41.8879020478639$$
$$x_{6} = -3.49065850398866$$
$$x_{7} = -68.0678408277789$$
$$x_{8} = -99.4837673636768$$
$$x_{9} = 22.6892802759263$$
$$x_{10} = -89.0117918517108$$
$$x_{11} = 27.9252680319093$$
$$x_{12} = -94.2477796076938$$
$$x_{13} = 64.5771823237902$$
$$x_{14} = 52.3598775598299$$
$$x_{15} = -38.3972435438752$$
$$x_{16} = -15.707963267949$$
$$x_{17} = 50.6145483078356$$
$$x_{18} = -73.3038285837618$$
$$x_{19} = 20.943951023932$$
$$x_{20} = 76.7944870877505$$
$$x_{21} = -52.3598775598299$$
$$x_{22} = -87.2664625997165$$
$$x_{23} = -29.6705972839036$$
$$x_{24} = 13.9626340159546$$
$$x_{25} = 57.5958653158129$$
$$x_{26} = 41.8879020478639$$
$$x_{27} = -61.0865238198015$$
$$x_{28} = -55.8505360638185$$
$$x_{29} = 45.3785605518526$$
$$x_{30} = -85.5211333477222$$
$$x_{31} = -69.8131700797732$$
$$x_{32} = 59.3411945678072$$
$$x_{33} = 31.4159265358979$$
$$x_{34} = -27.9252680319093$$
$$x_{35} = -66.3225115757845$$
$$x_{36} = 12.2173047639603$$
$$x_{37} = 10.471975511966$$
$$x_{38} = 43.6332312998582$$
$$x_{39} = 15.707963267949$$
$$x_{40} = 80.2851455917392$$
$$x_{41} = -83.7758040957278$$
$$x_{42} = 1.74532925199433$$
$$x_{43} = -54.1052068118242$$
$$x_{44} = 94.2477796076938$$
$$x_{45} = -71.5584993317675$$
$$x_{46} = 6.98131700797732$$
$$x_{47} = 85.5211333477222$$
$$x_{48} = 48.8692190558412$$
$$x_{49} = -40.1425727958696$$
$$x_{50} = 24.4346095279206$$
$$x_{51} = 36.6519142918809$$
$$x_{52} = 82.0304748437335$$
$$x_{53} = -82.0304748437335$$
$$x_{54} = 71.5584993317675$$
$$x_{55} = 38.3972435438752$$
$$x_{56} = -17.4532925199433$$
$$x_{57} = -92.5024503556995$$
$$x_{58} = 83.7758040957278$$
$$x_{59} = -33.1612557878923$$
$$x_{60} = 34.9065850398866$$
$$x_{61} = -36.6519142918809$$
$$x_{62} = -10.471975511966$$
$$x_{63} = 0$$
$$x_{64} = -50.6145483078356$$
$$x_{65} = -19.1986217719376$$
$$x_{66} = 29.6705972839036$$
$$x_{67} = 66.3225115757845$$
$$x_{68} = 17.4532925199433$$
$$x_{69} = -95.9931088596881$$
$$x_{70} = -97.7384381116825$$
$$x_{71} = -5.23598775598299$$
$$x_{72} = -45.3785605518526$$
$$x_{73} = 95.9931088596881$$
$$x_{74} = -22.6892802759263$$
$$x_{75} = -64.5771823237902$$
$$x_{76} = 69.8131700797732$$
$$x_{77} = 8.72664625997165$$
$$x_{78} = -26.1799387799149$$
$$x_{79} = -13.9626340159546$$
$$x_{80} = 99.4837673636768$$
$$x_{81} = 90.7571211037051$$
$$x_{82} = -80.2851455917392$$
$$x_{83} = 78.5398163397448$$
$$x_{84} = 97.7384381116825$$
$$x_{85} = 55.8505360638185$$
$$x_{86} = -78.5398163397448$$
$$x_{87} = -43.6332312998582$$
$$x_{88} = 3.49065850398866$$
$$x_{89} = -75.0491578357562$$
$$x_{90} = -31.4159265358979$$
$$x_{91} = -57.5958653158129$$
$$x_{92} = -24.4346095279206$$
$$x_{93} = -1.74532925199433$$
$$x_{94} = 68.0678408277789$$
$$x_{95} = 26.1799387799149$$
$$x_{96} = 92.5024503556995$$
$$x_{97} = 54.1052068118242$$
$$x_{98} = 89.0117918517108$$
$$x_{99} = -12.2173047639603$$
$$x_{100} = -59.3411945678072$$
$$x_{101} = -47.1238898038469$$