Circles

Question 1

What is the circumference?

Answer 1

The distance around the outside of the circle

C=2πr

Question 2

Formula for area of a circle.

Answer 2

A=πr2

Question 3

What is the radius?

Answer 3

A line from the centre of the circle to the edge.
r=C
2π

Question 4

What is the diameter?

Answer 4

A line from one side of the circle to the other, through the centre. d = 2r

Question 5

What is a tangent?

Answer 5

A straight line that just touches the circle.

Question 6

What is an arc?

Answer 6

Part of the circumference.

Question 7

What is a chord?

Answer 7

A line between two points of a circle.

Question 8

What is a sector?

Answer 8

An are of a circle - slice of pie.

Question 9

What is a segment?

Answer 9

Area between the arc and chord.

Question 10

The angle subtended at the centre is…

Answer 10

double the angle subtended at the circumference.

Question 11

Angles in a semi circle are…

Answer 11

90 degrees.

Question 12

A tangent to a circle makes…

Answer 12

90 degrees with the radius.

Question 13

A triangle formed by 2 radii is…

Answer 13

isosceles

Question 14

A diameter…

Answer 14

bisects a chord at 90 degrees.

Question 15

Opposite angles in a cyclic…

Answer 15

add to 180.

Question 16

Alternative

Answer 16

angle theorem

Question 17

Angles subtended by an arc..

Answer 17

in the same segment are equal.

Question 18

2 tangents from a single point outside the circle…

Answer 18

are the same length and form congruent triangles.