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To separate the variables, divide both sides of the equation by the product cos x cos y. This cancels cos x on the left side and cos y on the right side, resulting in (sin y)/(cos y)$dy = (\sin x)/(\cos x)dx$.

Conditions: The equation is a first-order differential equation.; cos x and cos y are not zero at the points of interest, allowing division.

To separate the variables, divide both sides of the equation by the product cos x cos y. This cancels cos x on the left side and cos y on the right side, resulting in (sin y)/(cos y)$dy = (\sin x)/(\cos x)dx$.

Conditions: The equation is a first-order differential equation.; cos x and cos y are not zero at the points of interest, allowing division.