Number Models 4

• How to show a number in an image:

  • (number->string 50) makes “50”
  • (text …) wrapped around that makes an image

  Example: (text (number->string 50) FONT-SIZE "purple") produces an image with the number 50 in FONT-SIZE point purple font.

• Make a dot follow the line y=2x-30 from x=0 to x=100. Repeat over from x=0 once the dot gets to 100.

• Draw a random radius circle (10<=r<=100) on the screen. Show the radius inside the circle.

  Writing check-expects is key to making this work!

• Make an animation of a point moving along the right-opening parabola x=y^2. The point should hit (0,0), (25,5), (100,10), (225,15), and (400,20) before repeating. The draw handler can be a little tricky too - make sure you test it so you know it works.

• Challenge: can you make the point hit (100,-10), (25,-5), (0,0), (25,5), and (100,10) instead?