Q15 of 112 Page 166

If the vertices of a Δ ABC are A(–4,4 ), B(8 ,4) and C(8,10). Find the equation of the straight line along the median from the vertex A.


Given: The ∆ABC with vertices A(–4,4),B(8,4) and C(8,10) and


AD is the median,i.e. it passes through the mid point of BC.


Therefore D is midpoint of BC where B(8,4) and C(8,10).



=


=


=


Equation of AD is


,where (x1,y1) and (x2,y2) are (–4,4) and (8,7)


⇒


⇒


⇒


⇒ 12(y–4) = 3(x + 4)


⇒ 12y–48 = 3x + 12


⇒ 12y–48–3x–12 = 0


⇒ –3x + 12y–60 = 0


⇒ 3x–12y + 60 = 0


⇒ x–4y + 15 = 0(Divide both sides of the equation by 3)


Hence Equation of AD is x–4y + 15 = 0.


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