<p><pre><code>    (define c
      (sqrt
       (sum (sqr a)
            (sqr b))))
</code></pre>
Which you read out loud like this: &quot;c is a square root of a sum of two values, squared&quot;.<p>Easy to read as you see and easy to understand. This:<p><pre><code>    c = sqrt(a*a+b*b)
</code></pre>
is way harder to read.