If you plug in the x values of both (2, 8) and (4, 12) into each equation, you'll find that y = 2x + 4 gives you the correct y values for both (2, 8) and (4, 12). So that is your answer.
So based on your question where there is a rectangle inscribed in a semicircle or a radius 10 as shown in your figure. The possible function that could represent the are of the rectangle is A=2x*sqrt(100-x^2) i hope you are satisfied with my answer and feel free to ask for more
<span>a rectangle rhombus(parallelogram) since even a parallelogram has diagonals</span>
4+4 is 8 lol thanks for the answer