**Joint Equation of Pair of Lines Type – I C **

**When Lines are Forming Equilateral Triangle With x = k or y = k**

**Problems shown in RED Colour are for Last Minute Revision (LMR)**

**ALGORITHM :**

1. Find angle made by the lines with positive direction of x-axis and calculate slopes m1 and m2 of the two lines.

2. Use y = mx form to find equations of the two lines.

3. Write equations of lines in the form u = 0 and v = 0.

4. Find u.v = 0.

5. Simplify the L.H.S. of joint equation.

### Problems for Practice:

- Find the joint equation of the straight lines through the origin which forms the equilateral triangle with the straight line x = 1.
- Find the joint equation of the straight lines through the origin which forms the equilateral triangle with the straight line y = 2.