1) #sin(theta+pi/4)=1/sqrt2=sin(pi/4)#
#=>x+pi/4=npi+(-1)^npi/4" whete "nin ZZ#
#=>x=npi+(-1)^npi/4-pi/4" whete "nin ZZ#
2) #tan(2theta-pi/4)+1=0#
#=>tan(2theta-pi/4)=-1=tan(-pi/4)#
#=>2theta-pi/4=npi-pi/4" whete "n in ZZ#
#=>theta=(npi)/2" whete "n in ZZ#