Straight Lines Lecture 4
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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 (x1, y1) and (h, k). If slope of the line is m, show that ky1 = m (hx1 ).

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