The coordinates of the three points A.B.C on the plane are (-5,-5),(-2,-1)and(-1,-2)respectively,the triangle ABC is( ) (英汉小词典:right直角的;isosceles等腰的;equilateral等边的;obtuse钝角的)
Suppose that in Fig.2,the length of side of square ABCD is 1,E and F are mid-points of CD and AD respectively,GE and CF intersect at a point P.Then the length of line segment CP is