Q. 85.0( 4 Votes )
Find the equations of the two straight lines through (1, 2) forming two sides of a square of which 4x + 7y = 12 is one diagonal.
Given: 4x + 7y = 12 is one diagonal and opposite vertex is (1,2)
To find: equation of straight line
Let A (1, 2) be the vertex of square ABCD and BD be the diagonal that is along the line 4x + 7y = 12
Here, we have to find the equations of sides AB and AD, each of which makes an angle of 45∘ with line 4x + 7y = 12
We know that the equations of two lines passing through a point x1,y1 and making an angle α with the line whose slope is m.
Equation of given line is
4x + 7y = 9
m, x1 = 1, y1 = 2, α = 45∘
So, the equations of the required sides are
⇒ 3x – 11y + 19 = 0 and 11x + 3y – 17 = 0
Hence, equation of straight line 3x – 11y + 19 = 0 and 11x + 3y – 17 = 0
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