**Basic Geometrical Ideas**

**Question 1.From the figure, identify:**

**(a)**the centre of circle

**(b)**three radii

**(c)**a diameter

**(d)**a chord

**(e)**two points in the interior

**(f)**a point in the exterior

**(g)**a sector

**(h)**a segment

**Solution:**

(a)O is the centre of the circle.

(a)

**(b)**OA, OB and OC are three radii of circle.

**(c)**AC is a diameter of circle.

**(d)**ED is a chord of circle.

**(e)**Points O and P are in the interior of circle.

**(f)**Point Q is in the exterior of circle.

**(g)**OAB is a sector of circle.

**(h)**Shaded region in the interior of a circle enclosed by a chord ED.

**Question 2.****(a)** Is every diameter of a circle also a chord?**(b)** Is every chord of a circle also a diameter?

**Solution:****(a)** Yes, a diameter is the longest chord.**(b)** Not always.

**Question 3.Draw any circle and mark**

**(a)**its centre

**(b)**a radius

**(c)**a diameter

**(d)**a Sector

**(e)**a segment

**(f)**a point in its interior

**(g)**a point in its exterior

**(h)**an arc

**Solution:**

Draw any circle and its various parts are as under :**(a)** Its centre is O.

**(b)**Its radii are OA, OB and OC.

**(c)**Its diameter is AOC.

**(d)**Its sector is OAB.

**(e)**Shaded region in the interior of a circle enclosed by a chord PQ.

**(f)**M is a point in its interior.

**(g)**N is a point in its exterior.

**(h)**BC is an arc.

**Question 4.Say true or false:**

**(a)**Two diameters of a circle will necessarily intersect.

**(b)**The centre of a circle is always in its interior.

**Solution:(a)** True, because each diameter passes through the centre of a circle.

**(b)**True.