(1) It is easy to know that the polar coordinates of A, B and C are (2, π/3), (2, π) and (2, 5π/3) respectively.

So the rectangular coordinates of A are (2cos(π/3), 2sin(π/3)), that is, (1, √3).

B (-2,0) and C( 1, -√3) can be obtained in the same way.

(2)|PA|^2+|PB|^2+|PC|^2

=(2cosφ- 1)^2+(3sinφ-√3)^2+(2cosφ+2)^2+(3sinφ-0)^2+(2cosφ- 1)^2+(3sinφ+√3)^2

= 12(cosφ)^2+27(sinφ)^2+ 12

= 15(sinφ)^2+24

By 0

(In fact, you can directly Baidu this question, and the answer will come out. )