Question

Question #c9664

Answer 1

`LHS=tan(alpha+beta) cos(alpha+beta)`

`=sin(alpha+beta)/cos(alpha+beta)xx cos(alpha+beta)`

`=sinalphacosbeta+cosalphasinbeta`

`=(cscalphasecalpha(sinalphacosbeta+cosalphasinbeta))/(cscalphasecalpha)`

`=(cscalphasecalphaxxsinalphacosbeta+cscalphasecalphacosalphasinbeta)/(cscalphasecalpha)`

`=(secalphacosbeta+cscalphasinbeta)/(cscalphasecalpha)=RHS`