A good answer might be:

The length is 5.0. You could use the formula, or by realize that this is another 3-4-5 right triangle.


Symbol for Vector Length

The formula works for vectors aligned with the axes: 

length of( (8,0)T )   =   ( 8*8 + 0*0 ) = 8

It is awkward to keep saying "length of ( )." There is a symbol for this: 

length of ( a )    =   | a |

Your browser might not show this well. The symbol a has a vertical bar on each side. Sometimes books use two vertical bars on each side. Using the new notation: 

| (x, y)T |   =   ( x2 + y2 )

QUESTION 5:

If   g   =   (1, 1)T,   what is   | g |   ?