Math Chapter Wise Ordinary And Partial Differential Equations, Integral Equations And Calculus Of Variations English MCQ UP PCS (Pre) 2008 Q.Solution of the differential equation sec2 x tan y dx+sec2 y tan x dy= 0 is Atan x + tan y = C Btan x tan y = C Ctan x – tan y = C Dtan x + sec y = C Show answer Correct answer: tan x tan y = C