Area and Perimeter


  1. A room 5.44 m x 3.75 m is to be paved with square tiles. the least number of tiles required to cover the floor is ?









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    Area of the room =(544 x 374) cm2
    size of largest square tile = H.C.F. of 544 & 374
    = 34 cm

    Correct Option: B

    Area of the room =(544 x 374) cm2
    size of largest square tile = H.C.F. of 544 & 374
    = 34 cm

    Area of 1 tile = (34 x 34) cm2

    ∴ Least number of tiles required
    = (544 x 374) / (34 x 34) = 176


  1. The ratio of the corresponding sides of two similar triangles is 3 : 4, The ratio of their areas is ?









  1. View Hint View Answer Discuss in Forum

    Ratio of similar triangle
    = Ratio of the square of corresponding sides
    = (3x)2 / (4x)2 = 9x2 / 16x2
    = 9/16 = 9 : 16

    Correct Option: C

    Ratio of similar triangle
    = Ratio of the square of corresponding sides
    = (3x)2 / (4x)2 = 9x2 / 16x2
    = 9/16 = 9 : 16



  1. A polygon has 44 diagonals the number of its sides is ?









  1. View Hint View Answer Discuss in Forum

    Let there be n sides of the polygon. Then it has n vertices.
    The total number of straight lines obtained by joining n vertices by talking 2 at a time is nC2
    These nC2 lines also include n sides of polygon.
    Therefore, the number of diagonals formed is nC2 - n.
    Thus, nC2 - n = 44

    Correct Option: C

    Let there be n sides of the polygon. Then it has n vertices.
    The total number of straight lines obtained by joining n vertices by talking 2 at a time is nC2
    These nC2 lines also include n sides of polygon.
    Therefore, the number of diagonals formed is nC2 - n.
    Thus, nC2 - n = 44
    ⇒ [n(n - 1)/2] - n = 44
    ⇒ ( n2 - 3n) / 2 = 44
    ⇒ n2 - 3n = 88
    ⇒ n2 - 3n - 88 = 0
    ⇒(n - 11) (n + 8) = 0
    ∴ n = 11


  1. A square, a circle and equilateral triangle have same perimeter.
    Consider the following statements.
    I. The area of square is greater than the area of the triangle.
    II. The area of circle is less then the area of triangle.
    Which of the statement is/are correct ?









  1. View Hint View Answer Discuss in Forum

    Let the radius of circle is 'r' and a side of a square is 'a',
    then given condition
    2πr = 4a
    ⇒ a = πr/2

    ∴ Area of square = (πr/2)2 = π2 /4r2 = 9.86r2/4 = 2.46r2
    and area of circle = πr2 = 3.14;r2
    and let the side of equilateral triangle is x.
    Then, given condition,
    3x = 2πr
    ⇒ x = 2πr/3

    ∴ Area of equilateral triangle = √3/4 x 2
    = √3/4 x 4π2r2/9
    = π2/3√3r2
    = 1.89r2

    Correct Option: A

    Let the radius of circle is 'r' and a side of a square is 'a',
    then given condition
    2πr = 4a
    ⇒ a = πr/2

    ∴ Area of square = (πr/2)2 = π2 /4r2 = 9.86r2/4 = 2.46r2
    and area of circle = πr2 = 3.14;r2
    and let the side of equilateral triangle is x.
    Then, given condition,
    3x = 2πr
    ⇒ x = 2πr/3

    ∴ Area of equilateral triangle = √3/4 x 2
    = √3/4 x 4π2r2/9
    = π2/3√3r2
    = 1.89r2

    Hence, Area of circle > Area of square > Area of equilateral triangle.



  1. If the area of an equilateral triangle is x and its perimeter is y, then which one of the following is correct ?









  1. View Hint View Answer Discuss in Forum

    Area of equilateral triangle = √3a2/4 = x ......(i)

    And perimeter = 3a = y
    ⇒ a = y/3 ....(ii)

    Now, Putting the value of a from Eq. (ii) in Eq. (i). we get
    3 (y/3)2/4 = x

    Correct Option: A

    Area of equilateral triangle = √3a2/4 = x ......(i)

    And perimeter = 3a = y
    ⇒ a = y/3 ....(ii)

    Now, Putting the value of a from Eq. (ii) in Eq. (i). we get
    3 (y/3)2/4 = x
    ⇒ x = √3 x y2/36
    ⇒ x = y2/3√3x = y2/12√3
    12√3 x = y2
    On squaring both sides, we get
    y4 = 432x2