Nobody can really answer this unless you can just give a random equation like 5*x=25 something like that
The awnser is 60 because
It is a cube so it has the smae amout of sides
Is there more to problem or is this it?
Seca(1-sina)(seca+tana)=1
Left hand side
=(1-sina) (seca +tana) / cosa
=seca +tana - sinaseca - sinatan / cosa
=seca + tana -tana -(sin^2a/cosa) / cosa
=(1/cosa - sin^2a/cosa) / cosa
= (1-sin^2a / cosa) / cosa
= (1-sin^2a)/ (cos^2a)
=1 (verified)