** “If you are not willing to risk the usual you will have to settle for the ordinary.”**

# Lecture - 4 Chapter 10 Straight Lines

EXERCISE 10.1 |

**Question 8. **Find the value of *x* for which the points (*x*, – 1), (2,1) and (4, 5) are collinear.

**Question 9. **Without using distance formula, show that points (– 2, – 1), (4, 0), (3, 3) and (–3, 2) are the vertices of a parallelogram.

**Question 10. **Find the angle between the x-axis and the line joining the points (3,–1) and (4,–2).

**Question 12. **A line passes through (*x*_{1}, *y*_{1}) and (*h*, *k*). If slope of the line is *m*, show that *k* – *y*_{1} = *m* (*h* – *x*_{1} ).

**Question 13. **If three points (*h*, 0), (*a*, *b*) and (0, *k*) lie on a line, show that \frac{a}{h} + \frac{b}{k} =1 .

**Question 14. **Consider the following population and year graph (Fig 10.10), find the slope of the line AB and using it, find what will be the population in the year 2010?

**Question 11. **The slope of a line is double of the slope of another line. If tangent of the angle between them is \frac{1}{3}, find the slopes of the lines.

Equation of line using area of triangle rule and collinear condition