(1) The coordinates of the three points A,B C on the plane are (-5,-5),(-2,-1)and(-1,-2),resoective

题目

(1) The coordinates of the three points A,B C on the plane are (-5,-5),(-2,-1)and(-1,-2),resoective
(1) The coordinates of the three points A,B C on the plane are (-5,-5),(-2,-1)and(-1,-2),resoectively,the triangle ABC is( )
A,a right triangle ,B an isosceles triangle C,an equilateral triangle D,an obtuse triangle


(2)Leta,b and c be rational numbers and b =12/5-13/5a, c=13/5-12/5a, then
aXa -bXb+cXc=（ ）

答案

第一个为等腰三角形,选B
第二个为1