Answer:
AB=4.9
Explanation:
Given: BK is an angle bisector of △ABC and BC=7, AK=3.5, KC=5.
To find: The value of AB.
Solution:
It is given that BK is an angle bisector of △ABC, therefore by using the angle bisector theorem we have
![(AB)/(BC)=(AK)/(KC)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/eh51mka4i38yo14i9cmc7j234asmb28b76.png)
Substituting the given values, we get
![(AB)/(7)=(3.5)/(5)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/jxq2ytnfczizsi1evjyuzeorivo2gsayyx.png)
On cross multiplying, we get
![AB=\frac{3.5{*}7}{5}](https://img.qammunity.org/2020/formulas/mathematics/middle-school/mmmgk6ug6xafnehm78sw37ozk2uoa7gj6l.png)
![AB=4.9](https://img.qammunity.org/2020/formulas/mathematics/middle-school/tmpg5gdmyofs3ohce4amya82s1rxpu4lf9.png)
Thus, the value of AB is 4.9