Coordinate Geometry Question 97

Question: If the coordinates of a point be given by the equations $ x=b\sec \varphi ,\y=a\tan \varphi $ , then its locus is

Options:

A) A straight line

B) A circle

C) An ellipse

D) A hyperbola

Show Answer

Answer:

Correct Answer: D

Solution:

Here $ \frac{x}{b}=\sec \varphi $ and $ \frac{y}{a}=\tan \varphi $ Therefore $ \frac{x^{2}}{b^{2}}-\frac{y^{2}}{a^{2}}={{\sec }^{2}}\varphi -{{\tan }^{2}}\varphi \Rightarrow \frac{x^{2}}{b^{2}}-\frac{y^{2}}{a^{2}}=1 $ , which is obviously a hyperbola.