Given: (tanx+tany)(1−cotxcoty)+(cotx+coty)(1−tanxtany) Formula Used: tan45∘=cot45∘=1 Calculation: (tanx+tany)(1−cotxcoty)+(cotx+coty)(1−tanxtany) We can easily solve it by value putting: Put x=y=45∘ ⇒(1+1)(1−1×1)+(1+1)(1−1×1) ⇒0+0 ⇒0 ∴ The value of (tanx+tany)(1−cotxcoty)+(cotx+coty)(1−tanxtany) is 0 .