√2(√2/2sina+√2/2coa)=1/5
√2sin(a+pi/4)=1/5
sin(a+pi/4)=√2/10
cos(a+pi/4)=-7√2/10
tan(a+pi/4)=-1/7
tana=tan[(a+pi/4)-pi/4]=(-1/7-1)/(1-1/7)=-8/6=-4/3