Sum of squares of two biggest numbers (SICP excercise)

scheme::sum_of_squares.scm

; pen test on functional programming
(define (min-2 a b) (if (> a b) b a))
(define (min-3 a b c) (min-2 (min-2 a b) (min-2 b c)))
(define (sq x) (* x x))
(define (foo a b c) (cond ((= a (min-3 a b c)) (+ (sq b) (sq c)))
                          ((= b (min-3 a b c)) (+ (sq a) (sq c)))
                          (else (+ (sq a) (sq b)))))