b)
tg35^0*tg55^0=tg35^0*tg(90^0-35^0)=tg35^0*ctg35^0=1
d)
sin18^0*cos72^0+cos18^0*sin72^0=
=sin18^0*cos(90^0-18^0)+cos18^0*sin(90^0-18^0)=
=sin18^0*sin18^0+cos18^0*cos18^0=sin^218^0+cos^218^0=1
e)
\frac{cos83^0}{sin7^0}-\frac{sin7^0}{cos83^0}=\frac{cos(90^0-7^0)}{sin7^0}-\frac{sin7^0}{cos(90^0-7^0)}=
=\frac{sin7^0}{sin7^0}-\frac{sin7^0}{sin7^0}=1-1=0