A point P lies on the line joining A(1, 2, 3) and B(2, 10, 1). If z-coordinate of P is 7, what is the sum of other two coordinates? 

Consider the following for the next two (02) items that follow :

Let A(1, -1, 2) and B(2, 1, -1) be the end points of the diameter of the sphere

x² + y² + z² + 2ux + 2vy + 2wz - 1 = 0.  

What is u + v + w equal to ? 

Consider the following for the next two (02) items that follow :

Let A(1, -1, 2) and B(2, 1, -1) be the end points of the diameter of the sphere

x² + y² + z² + 2ux + 2vy + 2wz - 1 = 0.  

P(x, y, z) is any point on the sphere, then what is PA² + PB² equal to ?  

Consider the following for the next two (02) items that follow :

Consider two lines whose direction ratios are (2, -1, 2) and (k, 3, 5). They are inclined at an angle $\frac{\pi}{4}$

What is the value of k?