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    In the given figure, a circle is inscribed in △PQR, such that it touches the sides PQ,QR and RP at points D,E,F, respectively. If the lengths of the s
    Question

    In the given figure, a circle is inscribed in △PQR, such that it touches the sides PQ,QR and RP at points D,E,F, respectively. If the lengths of the sides PQ=18 cm,QR=13 cm and RP=15 cm, then find the length of PD.

    A.

    10 cm

    B.

    8 cm

    C.

    15 cm

    D.

    12 cm

    Correct option is A

    Given:
    Side lengths: PQ=18 cm, QR=13 cm, RP=15 cm.
    A circle is inscribed in \triangle PQR, touching sides PQ, QR, and RP at points D, E, and F respectively.
    Concept Used:
    In a triangle, the lengths of the tangents drawn from an external point to a circle are equal. Therefore:
    PD=PF
    QD=QE
    RE=RF
    Solution: 
    PQ = PD + QD = x + y = 18 ...........(1)
    QR = QE + RE = y + z = 13.......(2)
    RP = RF + FP = z + x = 15.........(3)
    Add above three equations, we get
    2x+2y+2z = 46
    x+ y+z = 23.........(4)
    From equation 2, Put the value of y +z in equation 4, Then:
    x = 23 - 13 = 10
    So, PD = x = 10 cm

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