Given:
The figure of a triangle.
To find:
The missing length.
Solution:
Let x be the missing length.
Basic proportionality theorem(BPT): According to this theorem, if a line is parallel to the one side of a triangle then that the line intersects the other two sides of the triangle in the same ratio.
Using Basic proportionality theorem, we get
[tex]\dfrac{6}{8-6}=\dfrac{12-x}{x}[/tex]
[tex]\dfrac{6}{2}=\dfrac{12-x}{x}[/tex]
[tex]3=\dfrac{12-x}{x}[/tex]
[tex]3x=12-x[/tex]
Adding x on both sides, we get
[tex]3x+x=12[/tex]
[tex]4x=12[/tex]
[tex]x=\dfrac{12}{4}[/tex]
[tex]x=3[/tex]
The missing length is 3 Therefore, the correct option is D.
