Year 12s: what will be the first way you research your future options? >>

C2 Coordinate geometry

Here are the questions:

1) The points A(-3,19), B(9,11) and C(-15,1) lie on the circumference of a circle. Find the coordinates of the centre of the circle.

Midpoint = (^-3+9/₂, ¹⁹⁺¹¹/₂) = (-3,15)

^11-19/₉₊₃ = ^-3/₄

4y=-3x+51

Did the same for the other one, and got: M.P.(9,10) and 2y=3x-7

(4y=-3x+51) + (2y=3x+7) -> 6y=44 -> y=44/6=22/3

Is this right so far?

2) Find the distance between (-4a,0) and (3a,-2a)

d=√[(3a+4a)²+(-2a-0)²]
=√[(7a)²+(-2a)²]
=√[49a²+4a² = √53a²

Would the answer be √53a or 53a?