[填空题]
The diagram below shows a triangular bacf;(b0upjvnx 5 (cko)a 4xif8fkyard ABC. A dog is on a leash attached to a pole at point A. The length of the leash is 10 metrfi o8( f4xk)aces.
1.Find the area of the backyard that the dog cannot reach. $m^2$
The owner of the dog estimates that the area the dog cannot reach is $50 m^2$.
2.Calculate the percentage error in the dog owner's estimate. %