The ratio of bases of two triangles is $x : y$ and that of their areas is $a : b$. Then the ratio of their corresponding altitudes will be
Aptitude
Area
Difficulty: Medium
Choose an option
-
A$ax : by$
-
B$\frac{a}{x} : \frac{b}{y}$
-
C$ay : bx$
-
D$\frac{x}{a} : \frac{b}{y}$
Answer
Correct Answer: $ay : bx$
Explanation
### Concept & Ratio of Areas of Triangles
The area of a triangle is directly proportional to the product of its base and its altitude ($Area = \frac{1}{2} \times \text{base} \times \text{altitude}$).
### Step-by-Step Solution
* Let the bases of the two triangles be $k \cdot x$ and $k \cdot y$.
* Let their corresponding altitudes be $h_1$ and $h_2$.
* The ratio of their areas is given as $\frac{a}{b}$.
* Using the area formula:
$$\frac{\text{Area}_1}{\text{Area}_2} = \frac{\frac{1}{2} \cdot (k \cdot x) \cdot h_1}{\frac{1}{2} \cdot (k \cdot y) \cdot h_2}$$
* Substitute the given area ratio:
$$\frac{a}{b} = \frac{x \cdot h_1}{y \cdot h_2}$$
* Rearranging to solve for the ratio of the altitudes ($\frac{h_1}{h_2}$):
$$\frac{h_1}{h_2} = \frac{a \cdot y}{b \cdot x}$$
* Therefore, the ratio is $ay : bx$.
### Exam Strategy & Shortcut
Altitude is proportional to $\frac{\text{Area}}{\text{Base}}$. Therefore, the ratio of altitudes is simply $\frac{\text{Ratio of Areas}}{\text{Ratio of Bases}}$. Divide the area ratio terms by the base ratio terms: $\frac{a}{x} : \frac{b}{y}$, which simplifies to $ay : bx$ by cross-multiplying.
### Common Pitfall
Accidentally multiplying the ratios directly to get $ax : by$ instead of dividing them. Always set up the standard area fraction first to prevent this.
### Final Answer
Therefore, the correct answer is **$ay : bx$**.