cos@-5sin@\3cos@+sin@ tan@=2

cos@-5sin@\3cos@+sin@ tan@=2
cos@-5sin@\3cos@+sin@ tan@=2

cos@-5sin@\3cos@+sin@ tan@=2
(cos@-5sin@)\(3cos@+sin@) 分子分母同时除以 cos@
=(1-5tan@)/(3+tan@)
=(1-5×2)/(3+2)
=-9/5

tan@=2
sin@/cos@=2
sin@=2cos@

cos@-5sin@\3cos@+sin@
=cos@-5*2cos@\3cos@+2cos@
=11cos@\5cos@
=11\5