Plane Geometry


  1. Two equal circles of radius 4 cm intersect each other such that each passes through the centre of the other. The length of the common chord is :









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    According to question , we draw a figure of two equal circles of radius 4 cm intersect each other such that each passes through the centre of the other ,

    OC = 2cm
    OA = 4cm
    ∴ AC = √OA² - OC²
    ∴ AC = √4² - 2² = √16 - 4

    Correct Option: B

    According to question , we draw a figure of two equal circles of radius 4 cm intersect each other such that each passes through the centre of the other ,

    OC = 2cm
    OA = 4cm
    ∴ AC = √OA² - OC²
    ∴ AC = √4² - 2² = √16 - 4
    AC = √12 = 2√3
    ∴ AB = 4√3cm


  1. At least two pairs of consecutive angles are congruent in a _____.









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    As per the given in question , we draw a figure cyclic trapezium ABCD

    In an isosceles trapezium,
    AB || CD ; AD = BC
    AC = BD
    The angles of base are equal. i.e.

    Correct Option: B

    As per the given in question , we draw a figure cyclic trapezium ABCD

    In an isosceles trapezium,
    AB || CD ; AD = BC
    AC = BD
    The angles of base are equal. i.e.
    ∠A = ∠B ; ∠C = ∠D ; ∠A + ∠D = ∠B + ∠C = 180°



  1. ABCD is a trapezium in which AD || BC and AB = DC = 10 m. then the distance of AD from BC is :









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    According to question , we draw a figure of trapezium ABCD in which AD || BC and AB = DC = 10 m

    AE ⊥ BC; DF ⊥ BC
    ∴ ∠DCB = 45°
    In ∆ CDF,

    sin 45° =
    DF
    DC

    1
    =
    DF
    210

    Correct Option: C

    According to question , we draw a figure of trapezium ABCD in which AD || BC and AB = DC = 10 m

    AE ⊥ BC; DF ⊥ BC
    ∴ ∠DCB = 45°
    In ∆ CDF,

    sin 45° =
    DF
    DC

    1
    =
    DF
    210

    ⇒ DF =
    10
    = 5√2 metre.
    2


  1. If the parallel sides of a trapezium are 8 cm. and 4 cm., M and N are the mid-points of the diagonals of the trapezium, then length of MN is









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    As per the given in question , we draw a figure cyclic trapezium ABCD in which M and N are the mid-points of the diagonals ,

    The line segment joining the mid– points of the diagonals of a trapezium is parallel to each of parallel sides and is equal to half the difference of these sides.
    Here , AB = 8 cm. and CD = 4 cm

    ∴ MN =
    1
    (AB - CD)
    2

    Correct Option: D

    As per the given in question , we draw a figure cyclic trapezium ABCD in which M and N are the mid-points of the diagonals ,

    The line segment joining the mid– points of the diagonals of a trapezium is parallel to each of parallel sides and is equal to half the difference of these sides.
    Here , AB = 8 cm. and CD = 4 cm

    ∴ MN =
    1
    (AB - CD)
    2

    MN =
    1
    (8 - 4) cm. = 2 cm.
    2



  1. ABCD is a cyclic trapezium with AD || BC. If ∠A = 105°, then other three angles are









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    On the basis of question we draw a figure of trapezium ABCD with AD || BC ,

    AD || BC
    In concyclic quadrilateral ABCD,
    ∠A + ∠C = 180°
    ⇒ 105° + ∠C = 180°
    ⇒ ∠C = 180° – 105° = 75°
    Again,
    ∠A + ∠B = 180°
    ⇒ 105° + ∠B = 180°

    Correct Option: A

    On the basis of question we draw a figure of trapezium ABCD with AD || BC ,

    AD || BC
    In concyclic quadrilateral ABCD,
    ∠A + ∠C = 180°
    ⇒ 105° + ∠C = 180°
    ⇒ ∠C = 180° – 105° = 75°
    Again,
    ∠A + ∠B = 180°
    ⇒ 105° + ∠B = 180°
    ⇒ ∠B = 180° – 105° = 75°
    ∴ ∠D = 180° – 75° = 105°