Plane Geometry


  1. ABCD is a rectangle where the ratio of the length of AB and BC is 3 : 2. If P is the mid-point of AB, then the value of sin ∠CPB is









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

    Given , AB : BC = 3 : 2
    Let AB = 3y units and BC = 2y units

    ⇒ PB =
    3
    y units.
    2

    From ∆ PCB ,
    CP = √PB² + BC²
    CP = √
    9y²
    + 4y²
    4

    CP = √
    25y²
    =
    5y
    units
    42

    ∴ sin ∠CPB =
    BC
    CP

    sin ∠CPB =
    2y
    5y
    2

    sin ∠CPB =
    4
    5

    Take AB = 6y and BC = 4y ⇒ BP = 3y ⇒ CP = 5y

    Correct Option: D

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

    Given , AB : BC = 3 : 2
    Let AB = 3y units and BC = 2y units

    ⇒ PB =
    3
    y units.
    2

    From ∆ PCB ,
    CP = √PB² + BC²
    CP = √
    9y²
    + 4y²
    4

    CP = √
    25y²
    =
    5y
    units
    42

    ∴ sin ∠CPB =
    BC
    CP

    sin ∠CPB =
    2y
    5y
    2

    sin ∠CPB =
    4
    5

    Take AB = 6y and BC = 4y ⇒ BP = 3y ⇒ CP = 5y
    and sin ∠BPC =
    BC
    =
    4y
    =
    4
    CP5y5


  1. If the opposite sides of a quadrilateral and also its diagonals are equal, then each of the angles of the quadrilateral is









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    According to question , we draw a figure of rectangle ABCD

    AB = CD
    BC = AD
    AC = BD

    Correct Option: A

    According to question , we draw a figure of rectangle ABCD

    AB = CD
    BC = AD
    AC = BD
    It will be a rectangle and each angle will be a right angle.



  1. The length of the two adjacent sides of a rectangle inscribed in a circle are 5 cm and 12 cm respectively. Then the radius of the circle will be









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    As per the given question , we draw a figure of rectangle ABCD inscribed in a circle ,

    We know that , Diameter of circle = Diagonal of rectangle
    Here , BC = 12 cm. CD = 5 cm.
    ∴ BD = √BC² + CD²
    BD = √12² + 5²
    BD = √144 + 25
    BD = √169 = 13 cm.

    ∴ Radius of circle = BO =
    BD
    2

    Correct Option: B

    As per the given question , we draw a figure of rectangle ABCD inscribed in a circle ,

    We know that , Diameter of circle = Diagonal of rectangle
    Here , BC = 12 cm. CD = 5 cm.
    ∴ BD = √BC² + CD²
    BD = √12² + 5²
    BD = √144 + 25
    BD = √169 = 13 cm.

    ∴ Radius of circle = BO =
    BD
    2

    Radius of circle =
    13
    = 6.5 cm.
    2


  1. PQRA is a rectangle, AP = 22 cm, PQ = 8 cm. ∆ ABC is a triangle whose vertices lie on the sides of PQRA such that BQ = 2 cm and QC = 16 cm. Then the length of the line joining the mid points of the sides AB and BC is









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    On the basis of question we draw a figure of rectangle PQRA and ABC is a triangle whose vertices lie on the sides of PQRA ,

    Given that , QR = AP = 22 cm, PQ = 8 cm BQ = 2 cm and QC = 16 cm.
    ∴ CR = QR - QC = 22 – 16 = 6 cm.
    BC = √BQ² + QC²
    BC = √2² + 16²
    BC = √4 + 256
    BC = √260 cm.
    AC = √CR² + AR²
    AC = √6² + 8²
    AC = √36 + 64
    AC = √100 = 10 cm.

    Correct Option: B

    On the basis of question we draw a figure of rectangle PQRA and ABC is a triangle whose vertices lie on the sides of PQRA ,

    Given that , QR = AP = 22 cm, PQ = 8 cm BQ = 2 cm and QC = 16 cm.
    ∴ CR = QR - QC = 22 – 16 = 6 cm.
    BC = √BQ² + QC²
    BC = √2² + 16²
    BC = √4 + 256
    BC = √260 cm.
    AC = √CR² + AR²
    AC = √6² + 8²
    AC = √36 + 64
    AC = √100 = 10 cm.
    BD = DC
    BE = EA

    ∴ DE || AC and DE =
    1
    AC
    2

    DE = 10 ÷ 2 = 5 cm.



  1. ABCD is a cyclic quadrilateral. AB and DC are produced to meet at P. If ∠ADC = 70° and ∠DAB = 60°, then the ∠PBC + ∠PCB is









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    According to question , we draw a figure of cyclic quadrilateral ABCD in which AB and DC are produced to meet at P,

    ∠ADC = 70°
    ∠ABC = 180° – 70° = 110°
    ⇒ ∠PBC = 70°
    ∠BCD = 180° – 60° = 120°

    Correct Option: A

    According to question , we draw a figure of cyclic quadrilateral ABCD in which AB and DC are produced to meet at P,

    ∠ADC = 70°
    ∠ABC = 180° – 70° = 110°
    ⇒ ∠PBC = 70°
    ∠BCD = 180° – 60° = 120°
    ⇒ ∠PCB = 60°
    ∴ ∠PBC + ∠PCB = 70° + 60° = 130°