you have to use the identities an. It's trig

(Sec x + Csc x)(cos x+ sinx) ..... I used x instead of theata

= [1/cos x + 1/sinx] (cosx +sinx)

= [(sinx+ cosx)/cosxsinx]/ (cosx+sinx)

= 1/cosxsinx

=(1/cosx)x(1/sinx)= Secx Cosecx

Now you can replace theata for x.