Answer:
a = 7.2
Step-by-step explanation:
The figure has been re-labelled and attached to this response.
From the figure, the larger right triangle DAB and the small right triangle BCA are similar. This is because;
i. They have two corresponding congruent angles which are<em> the right angle</em>
and <em>angle B</em>
Therefore, we can say that;
<em>Cross multiply</em>
a x a = 13 x 4
a² = 52
a = √52
a = 7.2
Note: The figure showing the similar triangles has also been attached to this response.
