Find the length of the rectangle whose vertices are given.

A (2, 1), B (5, 4), C (0, 3), D (3, 6)

Distance between A and B

= Distance between C and D

= sqrt ((4 - 1) ^2 + (5 - 2) ^2)

= sqrt (3^2 + 3^2)

= sqrt (2 * 3^2)

= sqrt (3^2) * sqrt (2)

= 3sqrt (2)

Distance between B and C

= Distance between A and D

= sqrt ((4 - 3) ^2 + (5 - 0) ^2)

= sqrt (1^2 + 5^2)

= sqrt (26)

Since sqrt (26) is more than 3sqrt (2), the length must be sqrt (26).