Q.

A chord of a circle of radius 15 cm subtends an angle of 60° at the centre. Find the areas of the corresponding minor and major segments of the circle. (Use π = 3.14 and √3 = 1.73)

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By Expert Faculty of Sri Chaitanya

answer is 1.

(Detailed Solution Below)

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Detailed Solution

We know that,  formula for the area of the sector of a circle

Area of the sector = θ3600 × πr2

 Area of the segment  = Area of the sector - Area of the corresponding  triangle

Length of the arc = θ3600 × 2πr

 

A chord of a circle of radius 15 cm subtends an angle of 60° at the centre.  Find the areas of the corresponding minor and the major segments of the  circle. (Use

 

Here, r = 15 cm, θ = 600

 Area of minor segment APB = Area of sector OAPB - Area of ΔAOB

 Area of major segment AQB = πr2 - Area of minor segment APB

 

(i)Area of the sector = θ3600 × πr2

Area of the sector OABP= θ3600 × πr2

= 60°/360° × 3.14 × 15× 15

= 117.75 cm2

In ΔAOB,OA = OB = r

∠OBA = ∠OAB (Angles opposite to the equal sides in a triangle are equal)

∠AOB + ∠OBA + ∠OAB = 1800

60° + ∠OAB + ∠OAB = 1800

2 ∠OAB = 1200

∠OAB = 600

Therefore, ΔAOB is an equilateral triangle because all its angles are equal.

⇒ AB = OA = OB = r

Area of ΔAOB = √3/4 × (side)2

= √3/4 × r2

= √3/4 × (15 )2

= 1.73/4 × 225

= 97.3125 cm2

(i) Area of minor segment APB = Area of sector OAPB - Area of ΔAOB

= 117.75  - 97.3125

= 20.4375 cm2

(ii)Area of the major segment AQB = Area of the circle - Area of minor segment APB

=  π × (15)2 - 20.4375 

= 3.14 × 225  - 20.4375 

= 706.5  - 20.4375 

= 686.0625 cm2

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