tan(a+ b)=4,cot(a-b)=-3,→tan(a- b)=-1/3(1).tan2a=tan[(a+ b)+(a-b)]=[tan(a+b)+tan(a- b)]/[1-tan(a +b)tan(a- b)]=[4-1/3]/[1-4*(-1/3)=(11/3)/(7/3)=11/7(2).tan2b=tan[(a+ b)-(a-b)]=[tan(a+b)-tan(a- b)]/[1...