El gráfico de la función cruce el eje X con f = 0
o sea hay que resolver la ecuación:
$$\frac{\cos^{2}{\left(20 x \right)}}{\sin{\left(40 x \right)}} = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje X:
Solución numérica$$x_{1} = -64.009950316892$$
$$x_{2} = 68.2511003992383$$
$$x_{3} = 80.0320728502$$
$$x_{4} = -51.7577389678918$$
$$x_{5} = 100.295345465854$$
$$x_{6} = 98.2533102410208$$
$$x_{7} = -41.7046424764045$$
$$x_{8} = -91.9701249338412$$
$$x_{9} = -75.7909227678538$$
$$x_{10} = 46.2599518241097$$
$$x_{11} = 50.0298630084175$$
$$x_{12} = -31.9657052502761$$
$$x_{13} = 14.2157067574938$$
$$x_{14} = 54.2710130907637$$
$$x_{15} = -17.9856179418016$$
$$x_{16} = 8.24668071567321$$
$$x_{17} = 27.8816348006094$$
$$x_{18} = 44.2179165992763$$
$$x_{19} = -95.740036118149$$
$$x_{20} = 24.2688032489812$$
$$x_{21} = -59.7688002345458$$
$$x_{22} = 38.2488905574557$$
$$x_{23} = 25.9966792084555$$
$$x_{24} = 16.2577419823272$$
$$x_{25} = -35.7356164345839$$
$$x_{26} = 94.0121601586746$$
$$x_{27} = -7.77544181763474$$
$$x_{28} = 42.0188017417635$$
$$x_{29} = 77.9900376253666$$
$$x_{30} = -27.8816348006094$$
$$x_{31} = 48.1449074162636$$
$$x_{32} = 11.2311937365835$$
$$x_{33} = 40.4480054149686$$
$$x_{34} = 64.009950316892$$
$$x_{35} = -11.8595122673015$$
$$x_{36} = 88.3572933822129$$
$$x_{37} = 62.1249947247382$$
$$x_{38} = -39.9767665169301$$
$$x_{39} = 84.2732229325462$$
$$x_{40} = 90.2422489743668$$
$$x_{41} = -57.7267650097125$$
$$x_{42} = 36.2068553326224$$
$$x_{43} = -34.0077404751095$$
$$x_{44} = -37.7776516594173$$
$$x_{45} = 96.2112750161874$$
$$x_{46} = -43.7466777012379$$
$$x_{47} = -29.7665903927633$$
$$x_{48} = -61.9679150920587$$
$$x_{49} = -49.872783375738$$
$$x_{50} = 2.12057504117311$$
$$x_{51} = -23.6404847182632$$
$$x_{52} = -87.728974851495$$
$$x_{53} = 34.0077404751095$$
$$x_{54} = -4.00553063332699$$
$$x_{55} = 70.2931356240716$$
$$x_{56} = 74.2201264410589$$
$$x_{57} = -2.43473430653209$$
$$x_{58} = -79.8749932175205$$
$$x_{59} = 58.8263224384689$$
$$x_{60} = 86.0010988920206$$
$$x_{61} = -71.706852318187$$
$$x_{62} = -69.9789763587126$$
$$x_{63} = -55.9988890502381$$
$$x_{64} = 60.2400391325843$$
$$x_{65} = -97.7820713429823$$
$$x_{66} = -53.6426945600457$$
$$x_{67} = 30.2378292908018$$
$$x_{68} = -77.9900376253666$$
$$x_{69} = -65.7378262763664$$
$$x_{70} = 20.0276531666349$$
$$x_{71} = -45.7887129260712$$
$$x_{72} = 55.9988890502381$$
$$x_{73} = -21.7555291261093$$
$$x_{74} = -25.9966792084555$$
$$x_{75} = 22.2267680241478$$
$$x_{76} = 6.20464549083984$$
$$x_{77} = 52.2289778659303$$
$$x_{78} = -5.73340659280137$$
$$x_{79} = -81.7599488096744$$
$$x_{80} = -73.7488875430204$$
$$x_{81} = 82.2311877077128$$
$$x_{82} = -47.9878277835841$$
$$x_{83} = -67.7798615011998$$
$$x_{84} = -9.97455667514759$$
$$x_{85} = 32.1227848829556$$
$$x_{86} = -89.7710100763283$$
$$x_{87} = -15.7865030842887$$
$$x_{88} = 92.1272045665207$$
$$x_{89} = 4.00553063332699$$
$$x_{90} = 72.021011583546$$
$$x_{91} = 18.1426975744811$$
$$x_{92} = -86.0010988920206$$
$$x_{93} = 12.016591899981$$
$$x_{94} = -99.9811862004952$$
$$x_{95} = -83.4878247691488$$
$$x_{96} = -93.8550805259951$$
$$x_{97} = -13.7444678594553$$
$$x_{98} = 76.2621616658922$$
$$x_{99} = 66.2090651744049$$