Plane Geometry


  1. In a ∆ABC, if 2 ∠ A = 3 ∠ B = 6∠C, value of ∠ B is









  1. View Hint View Answer Discuss in Forum

    As per the given in question,
    ∴ 2∠A = 3∠B = 6∠C

    2∠A
    =
    3∠B
    =
    6∠C
    666

    ∠A
    =
    ∠B
    =
    ∠C
    321

    ⇒ ∠A : ∠B : ∠C = 3 : 2 : 1
    ∴ ∠B =
    2
    × 180°
    1 + 2 + 3

    Correct Option: A

    As per the given in question,
    ∴ 2∠A = 3∠B = 6∠C

    2∠A
    =
    3∠B
    =
    6∠C
    666

    ∠A
    =
    ∠B
    =
    ∠C
    321

    ⇒ ∠A : ∠B : ∠C = 3 : 2 : 1
    ∴ ∠B =
    2
    × 180°
    1 + 2 + 3

    ∠B =
    2
    × 180° = 60°
    6


  1. In a ∆ABC, ∠A + ∠B = 70° and ∠B + ∠C = 130°, value of ∠A is









  1. View Hint View Answer Discuss in Forum

    In ∆ ABC,
    As we know that , ∠A + ∠B + ∠C = 180°
    Given , ∠A + ∠B = 70° and ∠B + ∠C = 130°

    Correct Option: B

    In ∆ ABC,
    As we know that , ∠A + ∠B + ∠C = 180°
    Given , ∠A + ∠B = 70° and ∠B + ∠C = 130°
    ∴ ∠A = (∠A + ∠B + ∠C) – (∠B + ∠C)
    ∠A = 180– 130°= 50°



  1. Angle between sss ∠B is









  1. View Hint View Answer Discuss in Forum

    As per the given in question , we draw a figure of triangle ABC

    ∠BPC = 120°
    ∴ ∠PBC + ∠PCB = 180°– 120°= 60°

    Correct Option: D

    As per the given in question , we draw a figure of triangle ABC

    ∠BPC = 120°
    ∴ ∠PBC + ∠PCB = 180°– 120°= 60°
    ∴ ∠ABC + ∠ACB = 2 × 60° = 120°
    ∴ ∠A = 180 – 120 = 60°


  1. For a triangle ABC, D, E, F are the mid-points of its sides. If ∆ABC = 24 sq. units then ∆DEF is









  1. View Hint View Answer Discuss in Forum

    On the basis of given in question , we draw a figure triangle ABC ,

    Here , ∆ABC = 24 sq. units
    From figure , we have

    ∆DEF =
    1
    ∆ ABC
    4

    Correct Option: B

    On the basis of given in question , we draw a figure triangle ABC ,

    Here , ∆ABC = 24 sq. units
    From figure , we have

    ∆DEF =
    1
    ∆ ABC
    4

    ∆DEF =
    1
    × 24 = 6 Sq. unit
    4



  1. If I be the incentre of ∆ ABC and ∠B = 70° and ∠C = 50°, then the magnitude of ∠BIC is









  1. View Hint View Answer Discuss in Forum

    Firstly , We draw a figure of triangle ABC whose I is incentre ,

    Here , ∠B = 70° and ∠C = 50°

    ∠IBC =
    70°
    = 35° ;
    2

    ∠ICB =
    50°
    = 25° ;
    2

    Correct Option: C

    Firstly , We draw a figure of triangle ABC whose I is incentre ,

    Here , ∠B = 70° and ∠C = 50°

    ∠IBC =
    70°
    = 35° ;
    2

    ∠ICB =
    50°
    = 25° ;
    2

    We know that , ∠BIC + ∠ICB + ∠IBC = 180°
    ∴ ∠BIC = 180° – 35° – 25°
    ∠BIC = 180° – 60° = 120°