Question

In triangle $ABC,$ point $D$ is on $\overline{AC}$ such that $AD = 3CD = 12$. If $\angle ABC = \angle BDA = 90^\circ$, then what is $BD$?

Answer 1

Answer:

$BD=4\sqrt{3}\ units$

Step-by-step explanation:

we know that

$AD=12\ units$

$3CD=12$ ----> $CD=4\ units$

see the attached figure to better understand the problem

Triangles ABD and BCD are similar by AA Similarity Theorem

Remember that

If two figures are similar, then the ratio of its corresponding sides is proportional

so

$\frac{BD}{AD}=\frac{CD}{BD}$

substitute the given values

$\frac{BD}{12}=\frac{4}{BD}$

$BD^2=48$

$BD=\sqrt{48}\ units$

simplify

$BD=4\sqrt{3}\ units$