A rectangular parallelepiped is formed by drawing planes through the points (−1,2,5)and (1, -1, +1) and parallel to the coordinate planes. The length of the diagonal of the parallelepiped is

The planes forming the parallelepiped are x=−1,x=1;y=2,y=−1and z=5,=z−1 Hence, the lengths of the edges of the parallelepiped  are 1−(−1)=2,|−1−2|=3and |−1−5|=6(length of an edge of a rectangular parallelepiped is the distance between the parallel planes perpendicular to the edge)∴length of diagonal of the parallelepiped = =22+32+62=49=7