[填空题]
The diagram below showhql ,amxk1(u*ktc i,t4dru7 s k47ma5h c5w ;wuag* r0z.sg7gs a triangular backyard ABC. A dog is on a leash attached wa .hw;uzc0ggr7gs*5 to a pole at point A. The length of the leash is 10 metres.
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. %
