画一画:在点子图上各画一个直角和一个正方形,并且标出直角符号.:………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………