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# Lecture - 8 Chapter 10 Straight Lines

NCERT EXERCISE 10.2 |

**Question 14.Â **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.Â **The perpendicular from the origin to a line meets it at the point (â€“2, 9), find the equation of the line.

**Question 16.Â **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.Â **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.Â **Point R (*h*, *k*) divides a line segment between the axes in the ratio 1: 2. Find equation of the line.

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