# CBSE Class 10-Mathematics: Chapter – 12 Areas Related to Circles Part 6 (For CBSE, ICSE, IAS, NET, NRA 2022)

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**Question 10**:

A brooch is made with silver wire in the form of a circle with diameter 35 mm. The wire is also used in making 5 diameters which divide the circle into 10 equal sectors as shown in figure. Find:

(i) the total length of the silver wire required.

(ii) the area of each sector of the brooch.

**Answer**:

(i) Diameter

Circumference

Length of 5 diameters

Total length of the silver wire required

(ii)

The area of each sector of the brooch

**Question 11**:

An umbrella has 8 ribs which are equally spaced (see figure) . Assuming umbrella to be a flat circle of radius , find the area between the two consecutive ribs of the umbrella.

**Answer**:

Here,

Area between two consecutive ribs of the umbrella

**Question 12**:

A car has two wipers which do not overlap. Each wiper has a blade of length 25 cm sweeping through an angle of . Find the total area cleaned at each sweep of the blades.

**Answer**:

Here,

The total area cleaned at each sweep of the blades

**Question 13**:

To warn ships for underwater rocks, a lighthouse spreads a red colored light over a sector of angle to a distance of . Find the area of the sea over which the ships are warned.

**Answer**:

Here,

The area of sea over which the ships are warned

**Question 14**:

Tick the correct answer in the following:

Area of a sector of angle (in degrees) of a circle with radius R is:

(a)

(b)

(c)

(d)

**Answer: (D)**

Given,

Area of sector