2(sin78cos18 + sin 168sin198)=2(sin(90-12)cos18+sin(180-12)sin(180+18))=
2(cos12cos18-sin12sin18)=2cos(12+18)=2cos30=2*v3/2=v3
2(sin78cos18 + sin 168sin198)=2(sin(90-12)cos18+sin(180-12)sin(180+18))=
2(cos12cos18-sin12sin18)=2cos(12+18)=2cos30=2*v3/2=v3