Q 1 :

The area of a quadrant of a circle, whose circumference is 22 cm, is

  • 118cm2

     

  • 778cm2

     

  • 772cm2

     

  • 774cm2

     

(2)     778cm2

 

 



Q 2 :

The number of revolutions made by a circular wheel of radius 0.25m in rolling a distance of 11km is

  • 2800

     

  • 4000

     

  • 5500

     

  • 7000

     

(4)

Since, radius of wheel (r)=0.25m

Total distance covered by a circular wheel = 11 km = 11000 m

No. of revolutions×2πr=11000

No. of revolutions=11000×72×22×0.25=7000



Q 3 :

If the length of an arc of a circle subtending an angle 60° at its centre is 22 cm, then the radius of the circle is :

  • 21 cm

     

  • 21 cm

     

  • 42 cm

     

  • 42 cm

     

(2)      21 cm

 



Q 4 :

The diagonals of a rhombus ABCD intersect at O. Taking ‘O’ as the centre, an arc of radius 6 cm is drawn intersecting OA and OD at E and F respectively. The area of the sector OEF is :

  • 9π cm2

     

  • 3π cm2

     

  • 12π cm2

     

  • 18π cm2

     

(1)      9π cm2

 



Q 5 :

If the sum of the areas of two circles with radii R1 and R2 is equal to the area of a circle of radius R , then:

  • R1+R2=R

     

  • R12+R22=R2

     

  • R1+R2<R 

     

  • R12+R22<R2

     

(2)

According to the question,

πR12+πR22=πR2πR12+R22=πR2R12+R22=R2

 



Q 6 :

The area of the circle that can be inscribed in a square of side 6 cm is:

  • 36π cm2

     

  • 18π cm2

     

  • 12π cm2

     

  • 9π cm2

     

(4)

Let a circle with centre at O, having radius r, is inscribed in a square of side 6 cm as shown in Fig.

Diameter of the circle=6cm2r=6r=3 cmArea of circle=πr2=π×(3)2=9π cm2

 



Q 7 :

If the perimeter of a circle is equal to that of a square, then the ratio of their areas is:

  •  22:7

     

  • 14:11

     

  • 7:22

     

  • 11:14

     

(2)

Let r be the radius of the circle and x be the length of each side of the square.

According to the question, Perimeter of circle = Perimeter of square

2πr=4xπr=2xr=2xπ    (i)Area of circleArea of square=πr2x2=π×4x2π2x2=4πArea of circleArea of square=4227=4227×7=2822=1411Required ratio is 14:11

 



Q 8 :

If the area of a circle is 64π cm2  then its circumference is:

  • 7π cm

     

  • 16π cm

     

  • 14π cm

     

  • 21π cm

     

Let r be the radius of the circle. Then,

πr2=64πr2=64r=8 cmCircumference of the circle=2πr=2π×8 cm=16π cm



Q 9 :

If the areas of two circles are in the ratio 4:9, then the ratio of their perimeters of their semi-circles is:

  • 2:3 

     

  • 3:2

     

  • 1:2

     

  • 1:3

     

(1)

Let the radii of two circles be r1 and r2. It is given that

πr12:πr22=4:9r12:r22=4:9r1:r2=2:3Let P1 and P2 be the perimeters of the two semi-circles.Then,P1=πr1+2r1P2=πr2+2r2P1=(π+2)r1andP2=(π+2)r2P1:P2=r1:r2=2:3



Q 10 :

Which of the following statements are true regarding a circle of radius ‘R’?

(i) Area of circle=πR2(ii) Circumference of circle=πR(iii)Area of circleCircumference of circle=R2(iv) Area of circle is always greater than its circumference

Choose the correct option from the following:

  • (i) and (iii)

     

  • (ii) and (iii)
     

     

  • (iii) and (iv)

     

  • (i) and (iv)

     

(1)

Area ofcircle ofradius R=πR2Statement(i) is correct.Circumference of circle=2πR Statement (ii) is incorrect.Area of circle=πR2Area of circleCircumference of circle=πR22πR=R2 Statement (iii) is correctCircumference of circle=2πRLetstakeR=12, 2, 3WhenR=12Area=π4Perimeter=π Area < PerimeterWhen R=2Area=4π Perimeter=4π Area = Perimeter When R=3Area=9π Perimeter=6πArea>PerimeterSo, relation between area and perimeter of circle depends upon its radius.Statement (iv) is incorrect.