how the condition a[start]<=a[mid] is sufficient to say that mid belongs to the left line of the graph which is explained in the video?
Searching in sorted rotated array
Basically, if you have read the previous lectures of binary search, then you must be aware that there are two parts on which you have to check for values, using mid element, thus one start from start to mid, and other from mid+1 to end, so start to mid is your left part and other becomes your right part. Now the graph of sorted rotated array follows : first it increases, then it decrease and then again increase. Thus if your mid point lies on first half, then we say it is sorted, and hence you apply the condition for left part only.