`[sin(pix) + cos(piy)]^2 = 2`

Differentiating both sides w.r.t 'x' we get

`2[sin(pix) + cos(piy)]*[pi*cos(pix) - pi*sin(piy)*(dy/dx)] = 0`

`or, [pi*cos(pix) - pi*sin(piy)*(dy/dx)] = o`

`or, dy/dx = cos(pix)/sin(piy)`

``

`[sin(pix) + cos(piy)]^2 = 2`

Differentiating both sides w.r.t 'x' we get

`2[sin(pix) + cos(piy)]*[pi*cos(pix) - pi*sin(piy)*(dy/dx)] = 0`

`or, [pi*cos(pix) - pi*sin(piy)*(dy/dx)] = o`

`or, dy/dx = cos(pix)/sin(piy)`

``