El gráfico de la función cruce el eje T con f = 0
o sea hay que resolver la ecuación:
$$\cos^{2}{\left(t \right)} = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje T:
Solución analítica$$t_{1} = \frac{\pi}{2}$$
$$t_{2} = \frac{3 \pi}{2}$$
Solución numérica$$t_{1} = -61.2610562242523$$
$$t_{2} = -67.5442421675773$$
$$t_{3} = -83.2522055415057$$
$$t_{4} = 61.2610566752601$$
$$t_{5} = -70.685834448838$$
$$t_{6} = -98.960168684456$$
$$t_{7} = 67.5442422779275$$
$$t_{8} = -98.9601684414698$$
$$t_{9} = 86.393797888273$$
$$t_{10} = 32.9867226137576$$
$$t_{11} = -54.9778713137198$$
$$t_{12} = 61.2610569989704$$
$$t_{13} = 76.9690200400775$$
$$t_{14} = -10.9955745350309$$
$$t_{15} = 64.4026493086922$$
$$t_{16} = 45.553093700501$$
$$t_{17} = -26.7035372990183$$
$$t_{18} = -54.9778716831146$$
$$t_{19} = -95.8185758681287$$
$$t_{20} = -10.9955741902138$$
$$t_{21} = 98.9601685932308$$
$$t_{22} = -39.2699083866483$$
$$t_{23} = 23.5619449395428$$
$$t_{24} = 17.2787595624179$$
$$t_{25} = -4.71238872430683$$
$$t_{26} = -32.9867227513827$$
$$t_{27} = 70.6858345016621$$
$$t_{28} = -17.2787598091171$$
$$t_{29} = 73.8274274795554$$
$$t_{30} = 98.9601683381274$$
$$t_{31} = 95.8185760590309$$
$$t_{32} = 7.85398174058521$$
$$t_{33} = 83.2522052340866$$
$$t_{34} = 39.2699081179815$$
$$t_{35} = -76.9690202568697$$
$$t_{36} = -29.8451300963672$$
$$t_{37} = 76.9690197631883$$
$$t_{38} = 48.6946859238715$$
$$t_{39} = 32.986722928111$$
$$t_{40} = 36.1283156002139$$
$$t_{41} = 51.8362788999928$$
$$t_{42} = -58.1194639993376$$
$$t_{43} = -61.2610569641117$$
$$t_{44} = 58.1194644379895$$
$$t_{45} = 54.9778711883962$$
$$t_{46} = -70.6858346386357$$
$$t_{47} = 10.9955740392793$$
$$t_{48} = 4.71238876848081$$
$$t_{49} = -14.1371668392726$$
$$t_{50} = -23.5619450090417$$
$$t_{51} = -1.57079642969308$$
$$t_{52} = -7.85398149857354$$
$$t_{53} = 14.1371671048484$$
$$t_{54} = 76.9690207492347$$
$$t_{55} = 23.5619451230057$$
$$t_{56} = 20.4203521497111$$
$$t_{57} = 54.9778714849733$$
$$t_{58} = -73.8274272800405$$
$$t_{59} = 89.5353908552844$$
$$t_{60} = -86.393797765473$$
$$t_{61} = -89.5353907467661$$
$$t_{62} = -36.1283154192437$$
$$t_{63} = -51.8362786897497$$
$$t_{64} = -42.4115006098842$$
$$t_{65} = -4.7123889912442$$
$$t_{66} = -20.4203520321877$$
$$t_{67} = -26.7035375427973$$
$$t_{68} = -48.6946858738636$$
$$t_{69} = 92.6769830795146$$
$$t_{70} = 83.2522055730903$$
$$t_{71} = 17.2787598502655$$
$$t_{72} = 29.845130320338$$
$$t_{73} = -98.96016883042$$
$$t_{74} = -92.6769831823972$$
$$t_{75} = -92.6769830239371$$
$$t_{76} = 39.2699084246933$$
$$t_{77} = -17.2787590276524$$
$$t_{78} = -80.1106125795659$$
$$t_{79} = 80.1106126771746$$
$$t_{80} = -39.2699081528781$$
$$t_{81} = -32.9867231091652$$
$$t_{82} = -45.5530935883361$$
$$t_{83} = 541.924732890135$$
$$t_{84} = -76.9690198771149$$
$$t_{85} = 1.5707965454425$$
$$t_{86} = -64.4026491876462$$
$$t_{87} = 80.1106131434937$$
$$t_{88} = -48.6946860920117$$
$$t_{89} = 42.4115007291722$$
$$t_{90} = 26.7035373461441$$
$$t_{91} = 10.9955743696636$$