 (define (square x) (* x x)) 
  
 (define (squareSum x y) (+ (square x) (square y))) 
  
 (define (sumOfLargestTwoSquared x y z) 
   (cond ((and (>= (+ x y) (+ y z)) (>= (+ x y) (+ x z))) (squareSum x y)) 
         ((and (>= (+ x z) (+ y z)) (>= (+ x z) (+ x y))) (squareSum x z)) 
         (else (squareSum y z)) 
   ) 
 )

 (sumOfLargestTwoSquared 1 2 3) 
 ;Value: 13 
 (sumOfLargestTwoSquared 1 1 1) 
 ;Value: 2 
 (sumOfLargestTwoSquared 1 2 2) 
 ;Value: 8 
 (sumOfLargestTwoSquared 1 1 2) 
 ;Value: 5 
 (sumOfLargestTwoSquared 1 4 3) 
 ;Value: 25

mdsib

Here's a version with simpler logic to detect the smallest of the three values:

 (define (ssq a b) (+ (* a a) (* b b))) 
  
 (define (sumOfLargestTwoSquared x y z) 
   (cond ((and (<= x y) (<= x z)) (ssq y z)) 
         ((and (<= y x) (<= y z)) (ssq x z)) 
         (else (ssq x y))))

master

Another possibility (uses some language constructs that haven't been introduced yet):

  
 (define (square x) 
   (* x x)) 
  
 (define (sum-of-squares x y) 
   (+ (square x) (square y))) 
  
 (define (sum-of-squares-of-two-largest x y z) 
   (let* ((smallest (min x y z)) 
          (two-largest (remove smallest (list x y z)))) 
     (apply sum-of-squares two-largest)))

sicp-ex-1.3