sin10 *cos20*cos40*cos60 =(sin10 *cos10*cos20*cos40*cos60 )/cos10=0.5(sin20 *cos20*cos40*cos60 )/cos10=0.25(sin40 *cos40*cos60 )/cos10=0.125(sin80 *cos60 )/cos10=0.125(cos10 *cos60 )/cos10=0.125cos60=...