# Chapter 10 Straight Lines Lecture 8 Class 10 Maths

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# Lecture - 8 Chapter 10 Straight Lines

 NCERT EXERCISE 10.2

Question 14. Find equation of the line through the point (0, 2) making an angle $\frac{2 \pi}{3}$ with the positive x-axis. Also, find the equation of line parallel to it and crossing the y-axis at a distance of 2 units below the origin.

Question 15. The perpendicular from the origin to a line meets it at the point (–2, 9), find the equation of the line.

Question 16. The length L (in centimetre) of a copper rod is a linear function of its Celsius temperature C. In an experiment, if L = 124.942 when C = 20 and L= 125.134 when C = 110, express L in terms of C.]

Question 17. The owner of a milk store finds that, he can sell 980 litres of milk each week at Rs 14/litre and 1220 litres of milk each week at Rs 16/litre. Assuming a linear relationship between selling price and demand, how many litres could he sell weekly at Rs 17/litre?

Question 18. P (a, b) is the mid-point of a line segment between axes. Show that equation of the line is $\frac{x}{a}+ \frac{y}{b}= 2$.

Question 19. Point R (h, k) divides a line segment between the axes in the ratio 1: 2. Find equation of the line.

Question 20. By using the concept of equation of a line, prove that the three points (3, 0), (– 2, – 2) and (8, 2) are collinear.