<p><a href="http://mdtp.ucsd.edu/test_new/index.php">http://mdtp.ucsd.edu/test_new/index.php</a>
number 37 the one about BD= ?</p>
<p>This looks like some sort of college placement exam. Are you allowed to ask for help on it?</p>
<p>Nevertheless, how about a hint? Look for similar triangles. Let me know if you need any more help. Btw that problem can be solved with simple geometry; it’s not calculus.</p>