Circles: equations and tangents

Question 1 of 10

The radius of the circle x² + y² = 16 is ___

Question 2 of 10

The point (3, 4) lies on x² + y² = 25.

Question 3 of 10

A circle has exactly one centre.

Question 4 of 10

The centre of x² + y² + 2gx + 2fy + c = 0 is

Question 5 of 10

Find the gradient of the tangent to x² + y² = 13 at the point (2, 3).

Question 6 of 10

Find the equation of the circle with centre (2, −1) that passes through the point (5, 3).

Question 7 of 10

Find the centre of the circle x² + y² + 8x − 6y − 11 = 0.

Question 8 of 10

Write down the equation of the circle with centre (5, 3) and radius 7.

Question 9 of 10

The general equation of a circle is

Question 10 of 10

Find the centre and radius of the circle x² + y² − 6x + 4y − 12 = 0.