6.将极坐标系下的二次积分 (int )_(0)^dfrac (3pi {4)}dtheta (int )_(0)^1f(1+rcos theta ,rsin theta )rdr 转化为直角坐标系下的二-|||-次积分为 ()-|||-(A) (int )_(-dfrac {sqrt {2)}(2)dx(int )_(-x)^sqrt (-{x^2)}f(x,y)dy+(int )_(0)^1dx(int )_(0)^sqrt (-{x^2)}f(x,y)dy-|||-(int )_(dfrac {1)(2)}^1dfrac (1)(2)dx(int )_(1-x)^sqrt (-{(x-1)^2)}f(x,y)dy+(int )_(1)^2dx(int )_(0)^sqrt (-{(x-1)^2)}-|||-(int )_(0)^dfrac (sqrt {2)(2)}dy(int )_(-y)^sqrt (1-{y^2)}f(x,y)dx+int dfrac (sqrt {2)}(2)dy(int )_(-sqrt {-{y)^2}}f(x,y)dx-|||-(int )_(0)^dfrac (sqrt {2)(2)}dy(int )_(1-sqrt {1-{y)^2}}f(x,y)dx+(int )_(dfrac {sqrt {2)}(2)}^1dfrac (sqrt {2)}(2)dy(int )_(1+sqrt {-{y)^2