is it possible to do using sin or cos function with for loop
Yes, but you probably don't want to do that.
The curve you show is not a simple sine or cosine or simple sum or product of sines or cosines. However, since the curve has a finite number of samples (pixels), you could measure the coordinates on a pixel-by-pixel basis and then use an FFT to transform it into an implicit sum of sine waves, each with amplitude and phase. And then, with those amplitude and phase components on hand, you could go through the trouble of reconstructing the plot by calculating all of the sine components and adding them all up. That would be a loop using sine functions. But if you had all of the measurements needed to do this, it would be a lot more efficient to just plot in (x,y) coordinates directly.
Somewhere in the File Exchange is (or was!) a routine that could read image files and interpret the image as a graph to figure out what the data values were. Unfortunately I cannot seem to find the routine.
