I.G Semester Review G

Fall 2022, exam through Chapter 15 (conditionals), including gradients.

1. (in-5-r?) Imagine drawing a circle centered at x=5 on the x-axis, with a radius given by an input. A point x on the number line is in that circle if x’s distance to 5 is less than or equal to the radius.

   

   Write a function in-5-r? that determines if a number x is within “radius” of the number 5 on the number line.

    ;; in-5-r? : number(radius) number(x) -> boolean`
    (define (in-5-r? radius x)
      false)
    (check-expect (in-5-r? 10 3) true) ;; 3 is within 10 of 5
    (check-expect (in-5-r? 7 20) false) ;; 20 is not within 7 of 5
    (check-expect (in-5-r? 1 2) false) ;; 2 is not within 1 of 5
   

2. The circle is centered at (200,150) and has a radius of 50. The square is centered at (275,150) and has a side length of 100. The background is a gradient from light blue to light green. (These are technical color names in Racket.)

   

3. Make an animation where a blue circle moves counterclockwise around a stationary square.

   • Rotates as time passes.
   • Moving the mouse causes the rotation clockwise (while the mouse is moving).
   • Hitting a key makes the circle jump to the 12:00 vertical position.
   • Outer radius of the circle that the blue circle revolves along is 200.

   More complex aspects:

   • There is a 15 pixel wide pink bar on the left that grows 30 pixels taller every time the circle in the animation completes a single revolution.
   • The background changes color from a dark gray (all components = 100) to a light gray (all components = 225), proportional to the number of degrees the blue circle has traveled.

   

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