El gráfico de la función cruce el eje A con f = 0
o sea hay que resolver la ecuación:
$$\sin{\left(a \right)} \cos{\left(a \right)} = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje A:
Solución analítica$$a_{1} = 0$$
$$a_{2} = - \frac{\pi}{2}$$
$$a_{3} = \frac{\pi}{2}$$
Solución numérica$$a_{1} = 12.5663706143592$$
$$a_{2} = 78.5398163397448$$
$$a_{3} = -65.9734457253857$$
$$a_{4} = -15.707963267949$$
$$a_{5} = 86.3937979737193$$
$$a_{6} = -48.6946861306418$$
$$a_{7} = 50.2654824574367$$
$$a_{8} = 81.6814089933346$$
$$a_{9} = -64.4026493985908$$
$$a_{10} = 42.4115008234622$$
$$a_{11} = 73.8274273593601$$
$$a_{12} = 45.553093477052$$
$$a_{13} = 89.5353906273091$$
$$a_{14} = -75.398223686155$$
$$a_{15} = 590.619418874881$$
$$a_{16} = -1.5707963267949$$
$$a_{17} = -58.1194640914112$$
$$a_{18} = 56.5486677646163$$
$$a_{19} = -61.261056745001$$
$$a_{20} = -51.8362787842316$$
$$a_{21} = 15.707963267949$$
$$a_{22} = 7.85398163397448$$
$$a_{23} = -86.3937979737193$$
$$a_{24} = 58.1194640914112$$
$$a_{25} = 23.5619449019235$$
$$a_{26} = -67.5442420521806$$
$$a_{27} = -59.6902604182061$$
$$a_{28} = 21.9911485751286$$
$$a_{29} = 6.28318530717959$$
$$a_{30} = -119.380520836412$$
$$a_{31} = -87.9645943005142$$
$$a_{32} = -28.2743338823081$$
$$a_{33} = -9.42477796076938$$
$$a_{34} = -95.8185759344887$$
$$a_{35} = 59.6902604182061$$
$$a_{36} = 29.845130209103$$
$$a_{37} = 28.2743338823081$$
$$a_{38} = 80.1106126665397$$
$$a_{39} = 31.4159265358979$$
$$a_{40} = 94.2477796076938$$
$$a_{41} = -72.2566310325652$$
$$a_{42} = -80.1106126665397$$
$$a_{43} = 51.8362787842316$$
$$a_{44} = -29.845130209103$$
$$a_{45} = -97.3893722612836$$
$$a_{46} = 37.6991118430775$$
$$a_{47} = -483.805268652828$$
$$a_{48} = -20.4203522483337$$
$$a_{49} = -50.2654824574367$$
$$a_{50} = -94.2477796076938$$
$$a_{51} = -17.2787595947439$$
$$a_{52} = -40.8407044966673$$
$$a_{53} = 20.4203522483337$$
$$a_{54} = 67.5442420521806$$
$$a_{55} = 14.1371669411541$$
$$a_{56} = 4.71238898038469$$
$$a_{57} = -37.6991118430775$$
$$a_{58} = 70.6858347057703$$
$$a_{59} = -23.5619449019235$$
$$a_{60} = -83.2522053201295$$
$$a_{61} = -36.1283155162826$$
$$a_{62} = 1.5707963267949$$
$$a_{63} = 36.1283155162826$$
$$a_{64} = -81.6814089933346$$
$$a_{65} = 43.9822971502571$$
$$a_{66} = 95.8185759344887$$
$$a_{67} = -14.1371669411541$$
$$a_{68} = -31.4159265358979$$
$$a_{69} = 0$$
$$a_{70} = -21.9911485751286$$
$$a_{71} = -39.2699081698724$$
$$a_{72} = 26.7035375555132$$
$$a_{73} = -89.5353906273091$$
$$a_{74} = 100.530964914873$$
$$a_{75} = 34.5575191894877$$
$$a_{76} = 48.6946861306418$$
$$a_{77} = 65.9734457253857$$
$$a_{78} = -45.553093477052$$
$$a_{79} = 113.097335529233$$
$$a_{80} = -53.4070751110265$$
$$a_{81} = -7.85398163397448$$
$$a_{82} = 64.4026493985908$$
$$a_{83} = -6.28318530717959$$
$$a_{84} = -73.8274273593601$$
$$a_{85} = -43.9822971502571$$
$$a_{86} = 92.6769832808989$$
$$a_{87} = 72.2566310325652$$
$$a_{88} = -42.4115008234622$$
$$a_{89} = 87.9645943005142$$