There are multiple strategies we can use to find the diameter of a circle. For this question, we must calculate the length of the radius first and multiply by 2 to find the diameter.
We're given the centre and a point on the circumference: [tex](-2,1),(6,7)[/tex].
Find the distance between them using the distance equation:
[tex]d=\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}[/tex]
Plug in the given points:
[tex]d=\sqrt{(-2-x_1)^2+(1-y_1)^2}\\d=\sqrt{(-2-6)^2+(1-7)^2}\\d=\sqrt{(-8)^2+(-6)^2}\\d=\sqrt{64+36}\\d=\sqrt{100}\\d=10[/tex]
Therefore, the radius of the circle is 10 units.
Multiply the radius by 2 to find the length of the diameter:
10 × 2
= 20
Therefore, the length of the diameter is 20 units.
20 units