In the above figure, what are the values
[#permalink]
22 Dec 2024, 08:52
In the figure above, we have $\(\mathrm{OA}=\mathrm{a}, \mathrm{OB}=\mathrm{b}, \mathrm{BA}=\sqrt{\mathrm{a}^2+\mathrm{b}^2}, \mathrm{BC}=\mathrm{k}, \mathrm{CD}=\mathrm{x}\)$ \& $\(\mathrm{BD}=\sqrt{\mathrm{x}^2+\mathrm{y}^2}\)$ (Note: - $\(\mathrm{BA} \& \mathrm{BD}\)$ are found using Pythagoras theorem in triangle ABC \& triangle $\(B C D\)$ respectively)
Clearly $\(\triangle \mathrm{BOA} \sim \triangle \mathrm{BCD}\)$ (as $\(C D\)$ is parallel with $\(O A\)$ ), so using the similar triangle property (i.e. in similar triangles, the ratio of the corresponding sides is same), we get the $\(\frac{O B}{B C}=\frac{O A}{C D}=\frac{B A}{B D}\)$
i.e. $\(\frac{b}{k}=\frac{a}{x}=\frac{\sqrt{a^2+b^2}}{\sqrt{x^2+y^2}}\)$.
Now, $\(\frac{b}{k}=\frac{a}{x} \Rightarrow x=\frac{a k}{b}\)$ \& from the figure $\(C O=y=B O-B C=b-k\)$
Hence we get $\(x=\frac{a k}{b} \& y=b-k\)$, so the answer is $\((A)\)$.