Ctg 225°-ctg675°-cos495°+cos765°

Question

Ctg 225°-ctg675°-cos495°+cos765°

Answer 1

=Ctg(180+45)-ctg(720-45) -cos(90+45)+cos(720+45)=ctg45+ctg45-sin90+cos45=1+1-1+1/(√2)=(√2+1)/2