Help me on my geometry homework? :/

You could use a graphing calculator I just used Desmos. Origin is (0, 0). Rotate 90 degrees about the origin.

I used triangles

The rotated point would be at (1, 2)

ANSWER: the question mark = 1

From the attached graph, it is clear that the relation between x and y is linear as the graph between x and y is a straight line.

Step-by-step explanation:

Considering the data table

x                    y

0                   5

1                    9

2                   13

As there is constant change (increase) in x and y values

x values:       1 - 0 = 2 - 1 = 1

y - values:     9 - 5 = 13 - 9 = 4

So, the relation between x and y is linear.

Plotting the points (0, 5), (1, 9), (2, 13) to check the relation between x and y.

From the attached graph, it is clear that the relation between x and y is linear as the graph between x and y is a straight line.

The graph is attached below.