# Lecture 12 Chapter 10 Class 11 Maths Straight Lines

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# Lecture - 12 Chapter 10 Straight Lines

 NCERT EXERCISE 10.3

Question 14. Find the coordinates of the foot of perpendicular from the point (–1, 3) to the line 3x – 4y – 16 = 0.

Question 15. The perpendicular from the origin to the line y = mx + c meets it at the point (–1, 2). Find the values of m and c.

Question 16. If p and q are the lengths of perpendiculars from the origin to the lines $x \cos \theta – y \sin \theta = k \cos 2 \theta$ and $x \sec \theta + y \cosec \theta = k$, respectively, prove that $p^2+4q^2=k^2$.

Question 17. In the triangle ABC with vertices A (2, 3), B (4, –1) and C (1, 2), find the equation and length of altitude from the vertex A

Question 18. If p is the length of perpendicular from the origin to the line whose intercepts on the axes are a and b, then show that $\frac{1}{p^2}= \frac{1}{a^2}+\frac{1}{b^2}$.