(tryCatch (servlet (a b c) (case a ((#null) {Enter a,b,c}) (else (define p (+ a b c)) (define s (/ p 2)) (define area (sqrt (* s (- s a) (- s b) (- s c)))) {The area of a [a],[b],[c] triangle is [area]} ) ) ) (lambda(e) {There was an error:[e]. Be careful with my servlet} ) )