Plane Geometry


  1. In an equilateral Δ ABC, if AD ⊥ BC, then which option is true?











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    Lat AB = BC = AC = a
    AB2 = AD2 + BD2 (Pythagoras Theorem)


    Correct Option: C

    Lat AB = BC = AC = a
    AB2 = AD2 + BD2 (Pythagoras Theorem)

    a2 = AD2 +a2
    4

    3a2 = AD2
    4



  1. In the given figure, AB || DC, find the value of x.













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    As we know the diagonals of a trapezium divide each other proportionally

    AO = BO
    OCOD

    Correct Option: C

    As we know the diagonals of a trapezium divide each other proportionally

    AO = BO
    OCOD

    3x - 19 = x - 3
    x - 53

    ⇒ 3(3x - 19) = ( x - 3 ) ( x - 5 )
    ⇒ 9x - 57 = x2 - 8x +15
    ⇒ x2 - 17x + 72 = 0
    ⇒ x = 8 or x = 9



  1. In the adjoining figure ∠A + ∠B + ∠C + ∠D + ∠E + ∠F = ?













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    In ΔACE
    ∠A + ∠C + ∠E = 180°
    Similarly in ΔDFB
    ∠D + ∠F + ∠B = 180°

    Correct Option: C

    In ΔACE
    ∠A + ∠C + ∠E = 180°
    Similarly in ΔDFB
    ∠D + ∠F + ∠B = 180°
    ∴ (∠A + ∠C + ∠E) + (∠D + ∠F + ∠B) = 360°
    ∠A + ∠B + ∠C + ∠D + ∠E + ∠F = 360°


  1. In ΔABC, the angle bisectors of ∠B and ∠C meet at O. If ∠A = 70°, then ∠BOC is equal to:













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    As we know the formula,

    ∠BOC = 90° +1∠A
    2

    Correct Option: B

    As we know the formula,

    ∠BOC = 90° +1∠A
    2

    ∴∠BOC = 90° +1(70°) = 90° + 35°
    2

    ∠BOC = 125°



  1. The complement of an angle exceeds the angle by 60°. Then the angle is equal to:











  1. View Hint View Answer Discuss in Forum

    Let, the angle be A
    ⇒ Its complement angle = 90° – A
    According to the question
    (90 – A) = A + 60°

    Correct Option: C

    Let, the angle be A
    ⇒ Its complement angle = 90° – A
    According to the question
    (90 – A) = A + 60°
    ⇒ 90 - 60 = A + A
    ⇒ 2A = 30°
    ⇒ A = 15°