Learn the formula which is used for finding **distance between two parallel lines**. We can say that this is the important formula that we will study in 11^{th} coordinate geometry. Derivation of this formula no need, so just learn the formula.

We know that we have a formula for finding distance between two points in coordinate geometry. Similarly there is a formula for **distance between two parallel lines** also. Now let us know that formula.

**Use the below formula for finding distance between two parallel lines:**

Let us consider general form of two parallel lines. Let the two parallel lines be { a }_{ 1 } x + { b }_{ 1 } y + { c }_{ 1 } = 0 and { a }_{ 1 } x + { b }_{ 1 } y + { c }_{ 2 } = 0. We know that parallel lines differ only a constant. Therefore **distance between these two lines** is given by

Example:

If 4x + 3y + 30 = 0 and 4x + 3y + 10 = 0 be two parallel lines then find distance between them.

Solution:

Given parallel lines are

4x + 3y + 30 = 0

4x + 3y + 10 = 0

Therefore by substituting in formula we get

= \frac { 20 }{ 5 }

= 4

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