Plane Geometry


  1. Number of circles that can be drawn through three non-collinear points is :









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    One and only one circle can pass through three non-collinear points.

    Correct Option: A

    On the basis of given question ,
    We can say that One and only one circle can pass through three non-collinear points.


  1. The length of a chord which is at a distance of 12 cm from the centre of a circle of radius 13 cm is









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    As per the given in question , we draw a figure of a circle with centre O,

    OC ⊥ AB
    ∴ AC = CB
    OA = 13 cm. , OC = 12 cm.
    In ∆ OAC, AC = √OA² - OC²
    AC = √13² - 12²

    Correct Option: A

    As per the given in question , we draw a figure of a circle with centre O,

    OC ⊥ AB
    ∴ AC = CB
    OA = 13 cm. , OC = 12 cm.
    In ∆ OAC, AC = √OA² - OC²
    AC = √13² - 12²
    AC = √(13 + 12)(13 - 12)
    AC = √25 = 5 cm.
    ∴ AB = 2 AC = 10 cm.



  1. Points P, Q and R are on a circle such that∠PQR = 40° and ∠QRP = 60°. Then the subtended angle by arc QR at the centre is :









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    According to question , we draw a figure of a circle with centre O ,

    In ∆ PQR,
    ∠PQR = 40° ; ∠QRP = 60°
    ∴ ∠QPR = 180° – 60° – 40° = 80°

    Correct Option: D

    According to question , we draw a figure of a circle with centre O ,

    In ∆ PQR,
    ∠PQR = 40° ; ∠QRP = 60°
    ∴ ∠QPR = 180° – 60° – 40° = 80°
    ∴ Angle subtended at the circumference by arc QR = 80°
    ∴ Angle subtended at the centre by arc QR = ∠QOR = 2∠QPR = 2 × 80° = 160°


  1. Two circles touch each other externally. The distance between their centres is 7 cm. If the radius of one circle is 4 cm, then the radius of the other circle will be









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    On the basis of question we draw a figure of two circles touch each other externally ,

    Correct Option: A

    On the basis of question we draw a figure of two circles touch each other externally ,

    We know that , Distance between two circles = OO' = r1 + r2 = 7 cm.
    r1 = 4 cm.
    ∴ r2 = (7 – 4) cm. = 3 cm.



  1. The length of the radius of a circle with centre O is 5 cm and the length of the chord AB is 8 cm. The distance of the chord AB from the point O is









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    On the basis of question we draw a figure of a circle with centre O and radius is 5 cm ,

    Here , OA = radius = 5 cm.
    OC ⊥ AB

    ∴ AC = CB =
    8
    = 4 cm.
    2

    In right angle ∆ OAC,

    Correct Option: B

    On the basis of question we draw a figure of a circle with centre O and radius is 5 cm ,

    Here , OA = radius = 5 cm.
    OC ⊥ AB

    ∴ AC = CB =
    8
    = 4 cm.
    2

    In right angle ∆ OAC,
    OC = √OA² - AC² = √5² - 4²
    OC = √25 - 16 = √9 = 3 cm.