In triangle $\triangle ADC$, $DB$ is perpendicular to $AC$ at $B$ so that $AB=2$ and $BC=3$ as shown in the figure. Furthermore, $\angle ADC=45^\circ$ . Find the area of $\Delta ADC$.
Tried the following things:
- Drawing medians and altitudes of the right triangles formed.
- Apollonius's theorem.
- Stewart's theorem.
- Sine rule.
- Cosine rule.
- Noticing that $3+2$ equals to $5$, I extended segment $BD$ to form a 3-4-5 triangle and try to proceed.
Spent around 1.5 hours on it. In each of the cases, I wasn't able to proceed after a certain point.
Best Answer
$1=\tan(\alpha + \beta) = {\tan(\alpha)+\tan(\beta)\over 1-\tan(\alpha)\tan(\beta)}$
${\tan(\alpha) \over \tan(\beta)} = {2\over 3}$
Solve them you get $\tan(\beta)={1\over 2}$ so the height is $6$