Plane Geometry


  1. A circle (with centre at O) is touching two intersecting lines AX and BY. The two points of contact A and B subtend an angle of 65° at any point C on the circumference of the circle. If P is the point of intersection of the two lines, then the measure of ∠APO is









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

    Given , ∠ACB = 65°
    ∠AOB = 2 × ∠ACB = 2 × 65° = 130°

    Correct Option: A

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

    Given , ∠ACB = 65°
    ∠AOB = 2 × ∠ACB = 2 × 65° = 130°
    ∠OAP = 90°; ∠AOP = 65°
    ∴ ∠APO = 180° – 90° – 65° = 25°


  1. Chords AB and CD of a circle intersect externally at P. If AB = 6 cm, CD = 3 cm and PD = 5 cm, then the length of PB is









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    According to question , we draw a figure of a circle with two chords AB and CD ,

    Given , AB = 6 cm; CD = 3 cm
    PD = 5 cm; PB = ?
    We know that , PA × PB = PC × PD
    ⇒ (PB – 6) PB = 2 × 5
    ⇒ PB² – 6PB – 10 = 0

    ⇒ PB =
    6 ± √36 + 40
    2

    Correct Option: B

    According to question , we draw a figure of a circle with two chords AB and CD ,

    Given , AB = 6 cm; CD = 3 cm
    PD = 5 cm; PB = ?
    We know that , PA × PB = PC × PD
    ⇒ (PB – 6) PB = 2 × 5
    ⇒ PB² – 6PB – 10 = 0

    ⇒ PB =
    6 ± √36 + 40
    2

    PB =
    6 ± √76
    =
    6 + 8.7
    = 7.35 cm
    22



  1. If two equal circles whose centres are O and O', intersect each other at the point A and B, OO' = 12 cm and AB = 16 cm, then the radius of the circle is









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    On the basis of question we draw a figure of two circles with centres O and O' ,

    Here , AB = 16 cm and OO' = 12 cm
    AC = BC = 8 cm
    OC = CƠ = 6 cm
    ∴ OA = √OC² + CA²
    OA = √6² + 8²

    Correct Option: A

    On the basis of question we draw a figure of two circles with centres O and O' ,

    Here , AB = 16 cm and OO' = 12 cm
    AC = BC = 8 cm
    OC = CƠ = 6 cm
    ∴ OA = √OC² + CA²
    OA = √6² + 8²
    OA = √36 + 64
    OA = √100 = 10 cm


  1. Two parallel chords are drawn in a circle of diameter 30 cm. The length of one chord is 24 cm and the distance between the two chords is 21 cm. The length of the other chord is









  1. View Hint View Answer Discuss in Forum

    As per the given in question , we draw a figure circle

    Given , AB = 24 cm
    ⇒ AE = EB = 12 cm
    OE = √OA² - AE²
    OE = √15² - 12²
    OE = √225 - 144 = √81
    OE = 9 cm

    Correct Option: B

    As per the given in question , we draw a figure circle

    Given , AB = 24 cm
    ⇒ AE = EB = 12 cm
    OE = √OA² - AE²
    OE = √15² - 12²
    OE = √225 - 144 = √81
    OE = 9 cm
    ∴ OF = 21 – 9 = 12 cm
    Also, CF = √15² - 12² = 9 cm
    ∴ CD = 2 × CF = 2 × 9 = 18 cm



  1. A unique circle can always be drawn through x number of given non-collinear points, then x must be :









  1. View Hint View Answer Discuss in Forum

    As per the given question ,
    One and only circle can pass through three non-collinear points.

    Correct Option: B

    As per the given question ,
    We can say that One and only circle can pass through three non-collinear points.