Update app.py

fix error - InterpreterError: The variable math is not defined.

app.py

@@ -13,7 +13,7 @@ def monte_carlo_integration(func_expr: str, a: float, b: float, samples: int = 1
     """A tool that computes the approximate definite integral of a given function between limits a and b using Monte Carlo integration.
     
     Args:
-        func_expr: A string representing a mathematical function of x (e.g., "x**2 + 3*x + 2").
+        func_expr: A string representing a mathematical function of x (e.g., "x**2 + 3*x + 2" or "math.sin(x)").
         a: The lower bound of integration.
         b: The upper bound of integration.
         samples: The number of random samples to use for the approximation. Defaults to 10000.
@@ -24,9 +24,10 @@ def monte_carlo_integration(func_expr: str, a: float, b: float, samples: int = 1
     import random
     import math
 
-    # Define a safe evaluation context with math functions
+    # Create a safe dictionary of math functions and add the math module itself.
     safe_dict = {k: getattr(math, k) for k in dir(math) if not k.startswith("__")}
-    
+    safe_dict["math"] = math  # Allow expressions to use the 'math' prefix
+
     # Define the function to integrate safely using eval
     def f(x):
         try: