Sponsor Area

Coordinate Geometry

Question
CBSEENMA10009775

A(4, - 6), B(3,- 2) and C(5, 2) are the vertices of a ΔABC and AD is its median. Prove that the median AD divides ΔABC into two triangles of equal areas.

Solution

Let co-ordinate of D(x,y) and D is mid point of BC 

x = 3+52 = 4y = 2-22 = 0

                

Now area of triangle  ABD  =12{4(-2-0)+3[(0-(-6))]+4[(-6)--2]}                                          =0.5 x [-8+18-16]                                          =3 sq. unitAnd area of triangle ACD = 125-6-0 + 40-2 + 42+6                                               = 0.5 x -30 + -8 + 32                                               =  3 sq. unit  

Hence, the median AD divides triangle ABC into two triangles of equal area.