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Consider the following statements : 1 ...

Consider the following statements :
1 . For an equation of a line x cos q + y sin q = p , in normal form the length of the perpendicular from the point (a , b) to the line is |a cos q + b sin q + p|
2 The length of the perpendicular from the point `(alpha , beta)` to the line `(x)/(a) + (y)/(b) = 1` is `|(a alpha + b beta -ab)/(sqrt(a^(2) + b^(2)))|`
Which of the above statements is/are correct ?

A

1 only

B

2 only

C

Both 1 and 2

D

Neither 1 nor 2

Text Solution

AI Generated Solution

The correct Answer is:
To determine the correctness of the given statements about the lengths of perpendiculars from points to lines, we will analyze each statement step by step. ### Step 1: Analyze Statement 1 The first statement claims that for the line given in normal form \( x \cos q + y \sin q = p \), the length of the perpendicular from the point \( (a, b) \) to this line is \( |a \cos q + b \sin q + p| \). **Solution:** 1. The equation of the line can be rewritten as: \[ x \cos q + y \sin q - p = 0 \] 2. The formula for the length of the perpendicular from a point \( (x_0, y_0) \) to the line \( Ax + By + C = 0 \) is given by: \[ \text{Length} = \frac{|Ax_0 + By_0 + C|}{\sqrt{A^2 + B^2}} \] 3. Here, \( A = \cos q \), \( B = \sin q \), and \( C = -p \). Substituting \( (x_0, y_0) = (a, b) \): \[ \text{Length} = \frac{|a \cos q + b \sin q - p|}{\sqrt{\cos^2 q + \sin^2 q}} = |a \cos q + b \sin q - p| \] 4. The statement claims \( |a \cos q + b \sin q + p| \), which is incorrect. The correct expression should have a negative \( p \). **Conclusion for Statement 1:** Incorrect. ### Step 2: Analyze Statement 2 The second statement claims that the length of the perpendicular from the point \( (\alpha, \beta) \) to the line \( \frac{x}{a} + \frac{y}{b} = 1 \) is given by \( \left| \frac{a \alpha + b \beta - ab}{\sqrt{a^2 + b^2}} \right| \). **Solution:** 1. Rewrite the line equation: \[ \frac{x}{a} + \frac{y}{b} - 1 = 0 \implies bx + ay - ab = 0 \] 2. Here, \( A = b \), \( B = a \), and \( C = -ab \). 3. Using the formula for the length of the perpendicular: \[ \text{Length} = \frac{|b\alpha + a\beta - ab|}{\sqrt{b^2 + a^2}} \] 4. The statement claims \( |a\alpha + b\beta - ab| \), which is incorrect. The correct expression should have \( b\alpha + a\beta \). **Conclusion for Statement 2:** Incorrect. ### Final Conclusion Both statements are incorrect.
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Knowledge Check

  • Consider the following statements : 1. For an equation of a line, x cos q + y sin q = p , in normal form, the length of the perpendicular from the point (a, b) to the line is |a cos q+b sin q+p| . 2. The length of the perpendicular from the point (a, b) to the line x/a+y/b=1 is |(a alpha+b beta-ab)/sqrt(a^(2)+b^(2))| . Which of the above statements is/are correct ?

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    1 only
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    Both 1 and 2
    D
    Neither 1 nor 2
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    `|(b^(2) -ab +a^(2))/(sqrt(a^(2)+ b^(2)))|`
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    `|(b^(2) +ab -a^(2))/(sqrt(a^(2)+ b^(2)))|`
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