Concept:Use the tangent difference identity and express the result in terms of P=tan20∘.Explanation:The given expression is1+tan160∘tan110∘tan160∘−tan110∘.Using the identity tan(A−B)=1+tanAtanBtanA−tanB, the expression simplifies totan(160∘−110∘)=tan50∘.Now, tan50∘=tan(90∘−40∘)=cot40∘. Hence,tan50∘=tan40∘1.Using the double angle formula,tan40∘=tan(2×20∘)=1−tan220∘2tan20∘.Substituting P=tan20∘, we gettan40∘=1−P22P.Therefore,tan50∘=1−P22P1=2P1−P2.Answer:2P1−P2Correct option: D.