Plane Geometry


  1. If ∆PQR and ∆LMN are similar and 3PQ = LM and MN = 9 cm, then QR is equal to :









  1. View Hint View Answer Discuss in Forum

    As per the given in question , we draw figures of two similar triangles PQR and LMN

    Here , 3PQ = LM and MN = 9 cm
    ∆ PQR ~ ∆ LMN

    PQ
    =
    QR
    LMMN

    PQ
    =
    QR
    3PQ9

    Correct Option: D

    As per the given in question , we draw figures of two similar triangles PQR and LMN

    Here , 3PQ = LM and MN = 9 cm
    ∆ PQR ~ ∆ LMN

    PQ
    =
    QR
    LMMN

    PQ
    =
    QR
    3PQ9

    ⇒QR =
    1
    × 9 = 3 cm.
    3


  1. The perimeter of two similar triangles ABC and PQR are 36 cms and 24 cms respectively. If PQ = 10 cm then the length of AB is









  1. View Hint View Answer Discuss in Forum

    Given that , The perimeter of two triangles ABC and PQR are 36 cms and 24 cms. and PQ = 10 cm
    ∆ ABC ~ ∆ PQR

    AB
    =
    BC
    =
    AC
    PQQRPR

    =
    AB + BC + AC
    PQ + QR + PR

    AB
    =
    36
    AB
    =
    3
    PQ24102

    Correct Option: C

    Given that , The perimeter of two triangles ABC and PQR are 36 cms and 24 cms. and PQ = 10 cm
    ∆ ABC ~ ∆ PQR

    AB
    =
    BC
    =
    AC
    PQQRPR

    =
    AB + BC + AC
    PQ + QR + PR

    AB
    =
    36
    AB
    =
    3
    PQ24102

    ⇒ AB =
    3
    × 10 = 15 cm.
    2



  1. Which of the following is a true statement?









  1. View Hint View Answer Discuss in Forum

    If the corresponding sides of two triangles be proportional, the triangles are similar.

    Correct Option: C

    If the corresponding sides of two triangles be proportional, the triangles are similar. Hence , option C is correct answer .


  1. The perimeter of two similar triangles ∆ABC and ∆PQR are 60 cm and 36 cm respectively. If PQ = 18 cm, then AB is :









  1. View Hint View Answer Discuss in Forum

    Here , The perimeter of two similar triangles ∆ABC and ∆PQR are 60 cm and 36 cm
    and PQ = 18 cm
    ∆ ABC ~ ∆ PQR
    As we know that ,

    AB
    =
    BC
    =
    CA
    PQQRRP

    =
    AB + BC + CA
    PQ + QR + RP

    AB
    =
    60
    PQ36

    AB
    =
    60
    1836

    Correct Option: D

    Here , The perimeter of two similar triangles ∆ABC and ∆PQR are 60 cm and 36 cm
    and PQ = 18 cm
    ∆ ABC ~ ∆ PQR
    As we know that ,

    AB
    =
    BC
    =
    CA
    PQQRRP

    =
    AB + BC + CA
    PQ + QR + RP

    AB
    =
    60
    PQ36

    AB
    =
    60
    1836

    ⇒ AB =
    60
    × 18 = 30 cm.
    36



  1. Q is a point in the interior of a rectangle ABCD. If QA = 3 cm, QB = 4 cm and QC = 5 cm, then the length of QD (in cm) is









  1. View Hint View Answer Discuss in Forum

    According to question , we draw a figure of rectangle ABCD

    Given that , QA = 3 cm, QB = 4 cm and QC = 5 cm,
    Using Pythagoras theorem,
    QD² + QB² = QA² + QC²
    ⇒ QD² + 16 = 9 + 25
    ⇒ QD² = 34 – 16 = 18

    Correct Option: A

    According to question , we draw a figure of rectangle ABCD

    Given that , QA = 3 cm, QB = 4 cm and QC = 5 cm,
    Using Pythagoras theorem,
    QD² + QB² = QA² + QC²
    ⇒ QD² + 16 = 9 + 25
    ⇒ QD² = 34 – 16 = 18
    ⇒ QD = √18 = 3√2 cm