**Re: Year 11 Mathematics 3 Unit Cambridge Question & Answer Thread**

You didn't give us point A B and CQ 7 (b) EX 9A

I just wondering has there been a mistake in this answer of the 3U Year 11 textbook?

ii) ==> PA² + PB² + PC² = 3x² + 3y² - 14x - 6y + 78 = 77

==> 3x² + 3y² - 14x - 6y = -1

==> x² + y² - 14x/3 - 2y = -1/3

Grouping, (x² - 14x/3) + (y² - 2y) = -1/3

==> (x² - 14x/3 + 49/9) + (y² - 2y + 1) = -1/3 + 49/9 + 1

==> (x - 7/3)² + (y - 1)² = 55/9

The back of the book has the answer as (2,1) for centre and radius of