What is the value of y?

3 StartRoot 3 EndRoot units
6 StartRoot 3 EndRoot units
9 StartRoot 3 EndRoot units
12 StartRoot 3 EndRoot units

Note: You forgot to add the diagram, so I found the missing diagram and attached below, based on which I am solving your query. Hopefully, it would clear your concepts anyways.

Option B is correct, as    

Step-by-step explanation:

From the attached figure,

Δ is a right triangle.

Applying Pythagoras theorem,

switching sides

Note that Δ s also right triangle.

                    ∵

But length of a side can not be negative, so ignore the negative solution.

so

                   ∵

Therefore, option B is correct, as    

step-by-step explanation:

once you graph it hit 2nd (the blue button) and graph

that takes you to a table of coordinates

on the left is x coordinates and on the right is y coordinates and an empty box

(you may have to scroll up/down in order to get ( x, 0)

452,489 to the nearest thousand is 452,000