Question

Match the columns by referring to the definition given below.

"A conic is the locus of a point which moves in a plane so that its distance from a fixed point is in a constant ratio to its perpendicular distance from a fixed straight line”.

$\begin{array}{cc}\text{Definition}& \text{Name}\\ \text{P) Fixed point}& \text{1. Axis}\\ \text{Q) Fixed straight line}& \text{2. Vertex}\\ \text{R) Constant ratio}& \text{3. Directrix}\\ \text{S) Line passing through fixed point and perpendicular to fixed line}& \text{4. Focus}\\ & \text{5. Eccentricity}\end{array}$

• A. P - 3, Q - 4, R - 5, S - 1
• B. P - 4, Q - 3, R - 5, S - 2
• C. P - 4, Q - 3, R - 5, S - 1
• D. P - 4, Q - 3, R - 1, S - 5

Answer 1

The correct option is C

P - 4, Q - 3, R - 5, S - 1

The fixed point in the definition is S and the fixed line is L.we call them focus and directrix respectively.

P is our moving point .PM is the perpendicular distance from directrix(L).

The constant ratio $\frac{PS}{PM}$ is called the eccentricity (e).

From S,we can draw a line perpendicular to directrix.This line is called axis.

These are based on definition.But we will be using them in most of the questions.