NDA Maths Mock Test – 01 – Q102

The solution of the differential equation cos x sin y dx + sin x cos y dy = 0 is:

• sin x sin y = c
• cos x cos y = c
• sin x / sin y = c
• sin x + sin y = c

i Gi√en differential equation is
‘ cos x siny dx +sinx cos y dy =0
1 = cos x siny dx =-sin x cos y dy
:
1 ede = Edy I
‘ = cot x dx = -coty dy ‘
On integrating both sides, we get
‘ Jcotazdz = — cot ydy i
‘ log Isin xI =- log I’siny I + log C
hon a
‘ = logIsinxsinyl=1logC ‘
= sinx.siny=C