Exercise 1.11

• Your definitions for this exercise should only make use of calls to the procedures filled-triangle and overlay; they are not lambda expressions.

• Your definitions for part a should have the form:

      (define corner-bb image-expr )
  
      (define rcross-bb image-expr )

  where image-expr is an appropriate combination of image procedure calls that results in the given basic block.

• For part b you must name your own basic block my-bb. Its definition should have the form:

      (define my-bb image-expr )