What is the equation of the straight line which passes through the point of intersection of the straight lines x + 2y = 5 and 3x + 7y = 17 and is perpendicular to the straight line 3x + 4y = 10?
What is the equation of the straight line which passes through the point of intersection of the straight lines x + 2y = 5 and 3x + 7y = 17 and is perpendicular to the straight line 3x + 4y = 10? Correct Answer 4x – 3y + 2 = 0
Concept:
- When two lines are perpendicular, the product of their slope is -1. If m is the slope of a line, then the slope of a line perpendicular to it is -1/m.
- Equation of line is (y – y1) = m(x – x1)
Calculation:
x + 2y = 5 …. (1)
3x + 7y = 17 …. (2)
Solving equation 1 and 2, we get
x = 1 and y = 2
Point of intersection: (x, y) = (x1, y1) = (1, 2)
Let slope of the straight line 3x + 4y = 10 is m1,
∴ Slope (m1) = -3/4
We know that when two lines are perpendicular, the product of their slope is -1.
Slope of perpendicular line = -1/m1 = 4/3 = m
Equation of line: (y – y1) = m(x – x1)
⇒ y – 2 = 4/3 (x – 1)
⇒ 3y – 6 = 4x – 4
∴ 4x – 3y + 2 = 0
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Feb 20, 2025