Answer? +b？ +c？ +2ab+2bc+2ac=3a？ +3b？ +3c？
2a？ -2ab+2b？ -2bc-2ac+2c？ =0
(a-b)? +(b-c)？ +(A-C)? =0
∴a-b=0 b-c=0 a-c=0
∴a=b=c
Delta is an equilateral triangle.
What does the basic knowledge of a primary education major contain?
Master the basic theory, knowledge and skills of this major; Wide knowledg