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    In triangle ABC, D is the mid-point of BC. If DL perpendicular to AB and DM perpendicular to AC such that DL = DM, then the triangle will be:
    Question

    In triangle ABC, D is the mid-point of BC. If DL perpendicular to AB and DM perpendicular to AC such that DL = DM, then the triangle will be:

    A.

    isosceles triangle

    B.

    right angled triangle

    C.

    obtuse angle triangle

    D.

    equilateral triangle

    Correct option is A

    Given:
    DDD is the mid-point of BCBCBC.
    DL⊥ABDL \perp ABDLAB, and DM⊥ACDM \perp ACDMAC.
    DL=DMDL = DMDL=DM.   
    Concept Used:  
    If two triangle have one side , hypotenuse and right angle equal to each other,
    then both triangles are congruent through RHS congruency. 
    Solution:
    In BDL\triangle BDL and CDM\triangle CDM 
    DL = DM 
    L=M=90\angle L = \angle M = 90^\circ 
    BD = CD ( D is mid point of BC) 
    So, BDLCDM△BDL \cong△CDM  ( RHS congruency)
    thus BL = CM .... (1)
    In ALD\triangle ALD and AMD\triangle AMD 
    AD = AD (common)
    L=M=90\angle L = \angle M = 90^\circ 
    DL = DM  
    therefore, ALDAMD △ALD≅△AM D (RHS congruency)
    thus, AL = AM .... (2)
    from (1) and (2) 
    we get  AB = AC 
    Therefore, ABC\triangle ABC is an isosceles triangle.

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