Question

the circumference of the circle 45x2+ 45y2-60x+36y+19=0

Answer 1

Answer:

Do the "complete the square" for x and y..

(45x^2 -60x) + (45y^2 + 36y) + 19 = 0

==> (x^2 - 60x/45) + (y^2 +36y/45) = -19/45

==> (x^2 -4x/3) + (y^2 + 4y/5) = -19/45

==> (x^2 - 4x/3 + 4/9) + (y^2 + 4y/5 + 4/25) = -19/45 + 4/9 + 4/25

==> (x - 2/3)^2 + (y +2/5)^2 = 41/225

so radius is (√41)/5