Answer:
Option D -8.3 cm, 5.8 cm
Step-by-step explanation:
Given : An angle bisector of a triangle divides the opposite side of the triangle into segments 6 cm and 5 cm long. A second side of the triangle is 6.9 cm long.
To find : The longest and shortest possible lengths of the third side of the triangle?
Solution :
First we create the image of the question,
Refer the attached figure below.
Let a triangle ABC , where angle A has a bisector AD such that D is on the side BC.
The theorem is stated for angle bisector is
"Each angle bisector of a triangle divides the opposite side into segments proportional in length to the adjacent sides".
So, according to question,
Let BD=6 cm, DC=5 cm, AB=6.9 cm
and we have to find AC.
Applying the theorem,
[tex]\frac{BD}{DC}=\frac{AB}{AC}[/tex]
[tex]\frac{6}{5}=\frac{6.9}{AC}[/tex]
[tex]AC=\frac{6.9\times 5}{6}[/tex]
[tex]AC=\frac{34.5}{6}[/tex]
[tex]AC=5.75[/tex]
[tex]AC=5.8 cm[/tex]
If we let AC=6.9 cm, find AB
Then,
[tex]\frac{BD}{DC}=\frac{AB}{AC}[/tex]
[tex]\frac{6}{5}=\frac{AB}{6.9}[/tex]
[tex]AB=\frac{6.9\times 6}{5}[/tex]
[tex]AB=\frac{41.4}{6}[/tex]
[tex]AB=8.28[/tex]
[tex]AB=8.3 cm[/tex]
Therefore, The shortest possible length is 5.8 cm and longest possible is 8.3 cm.
Hence, Option D is correct.
