There is a rectangular sheet of dimension , where . It has been divided into square of unit area by drawing lines perpendicular to the sides. Find number of rectangles having sides of odd unit length.
(m + n + 1)2
mn (m + 1)(n + 1)
4m + n - 2
m2n2
what does it mean by odd unit length? if a number is greater than 1 how it would be unit?