Question

What is the length in units of the blue line in the square below?

Answer 1

In this problem we have two blue lines

Each blue line has a length of 6 units

therefore

Multiply the length of one blue line by 2

2*6=12 units

the answer is

12 units

Part 2

we have that

The x-coordonate of point D is 3

the y-coordinate of point D is 6

therefore

the coordinates of point D are (3,6)