Chapter 4: Basic Geometrical Ideas

(a) The centre of the circle is O

(b) Three radii are , , 

(c) A diameter is 

(d) A chord is 

(e) Two points in the interior are O and P

(f) A point in the exterior is Q

(g) A sector is AOB, i.e., shaded region

(h) A segment is ED, i.e., shaded region

(a) Yes, every diameter of a circle is also a chord. The diameter is also called the longest chord.

(b) No, every chord is not a diameter.

(a) The centre of the circle is O.

(b) The radius is OC

(c) A diameter is 

(d) A sector is AOC

(e) A segment is DE

(f) A point in its interior is O

(g) A point in its exterior is F

(h) An arc is 

(a) True, two diameters will always intersect each other at the centre of the circle.

(b) True, the centre of the circle will always be in its interior.

Disclaimer: 

Dropped Topics – 4.11 Triangles, 4.12 Quadrilaterals,  4.13 Circles .