Python 3.2.3 ValueError: could not convert string to float
<pre><code>import math
pi = 3.1415

r = float(input("Enter the radius: "))
angle = float(input("Enter the angle: "))
x = r * math.cos(angle)
y = r * math.sin(angle)

print ('x =', x, 'y =', y)
</code></pre>

<p>When I enter pi, or anything with pi, as answer for angle prompt, I get this error:</p>

<pre><code>ValueError: could not convert string to float: 'pi'
</code></pre>

<p>Any suggestions what to do?</p>
