Read ALL instructions. Click on the green flag. Go to Presentation Mode. If you have a laptop, set the screen perpendicular to the keyboard. Take a ten-inch piece of small chain like that used to turn on and off light fixtures or a chain necklace. Grasp the left end of the chain with your left thumb and forefinger, the right end with your right thumb and forefinger, set your thumbs over points A and B, and adjust the length of the chain until it matches the shape of the curve on the screen. You will observe that the chain does indeed assume the shape of the catenary described by the equation.
The catenary curve is the curve formed by a flexible chain when supported at both ends and allowed to hang. Gravity forms the curve. The catenary curve is drawn from x = 0 and then to the right along the positive X-axis. Each positive x-value is reflected in the Y-axis. If you 'See inside' you will note that a= 150. My other 'catenary' project, A Boy and his Kite, can be seen at: https://scratch.mit.edu/projects/72364954/
