07 Circles

Question 1

What is the equation of a circle?

Answer 1

(x - a)^2 + (y - b)^2 = r^2

Question 2

What is (a,b) in the equation of the circle?
* (x - a)^2 + (y - b)^2 = r^2*

Answer 2

The centre of the circle.

Question 3

What is r in the equation of the circle?
* (x - a)^2 + (y - b)^2 = r^2*

Answer 3

The radius

Question 4

How do you find the equation of the circle when it’s in expanded form?

Answer 4

Complete the square for both x and y values.

Question 5

Which circle theorem is this?

Answer 5

The angle in a semicircle is a right angle.

Question 6

What is this circle theorem?

Answer 6

A tangent to a circle is perpendicular to the radius of the circle at the point of intersection.

Question 7

what are these circle theorems?

Answer 7

-the perpendicular bisector of a chord will go through the centre of the circle.
-the shortest distance from the centre of the circle to the chord is the perpendicular bisector.

Question 8

If the discriminant > 0 then how many times does the line intersect the circle?

Answer 8

2

Question 9

If the discriminant = 0 then how many times does the line intersect the circle?

Answer 9

1 (tangent)

Question 10

If the discriminant < 0 then how many times does the line intersect the circle?

Answer 10

Doesn’t intersect.