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Grade 12th passAnalytical Geometry

find the angle between the two st lines 3x=4y+7 and 5y=12x+6 and also the equations to the two lines which pass through the point (4,5) and make equal angles with the two given lines

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Profile image of Tejas Jaiswal
11 Years agoGrade 12th pass
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1 Answer

Profile image of Jitender Singh
11 Years ago
Ans:
Hello student,
Please find answer to your question below

4y = 3x - 7…...........(1)
5y = 12x + 6............(2)
m_{1} = \frac{3}{4}, m_{2} = \frac{12}{5}
Angle b/w two lines:
tan\theta = |\frac{m_{1}-m_{2}}{1+m_{1}m_{2}}|
tan\theta = |\frac{\frac{3}{4}-\frac{12}{5}}{1+\frac{3}{4}.\frac{12}{5}}|
tan\theta = |\frac{-33}{56}| = \frac{33}{56}
\theta = tan^{-1}\frac{33}{56}
Let the slope of the lines be ‘m’ which make equal angle with these lines
Then
\frac{m-\frac{3}{4}}{1+m.\frac{3}{4}} = \pm \frac{m - \frac{12}{5}}{1+m.\frac{12}{5}}
(4m-3)(12m+5) = \pm (3m+4)(5m-12)
(48m^{2}-16m-15) = \pm (15m^{2}-16m-48)
+ve sign is not possible
63m^{2}-32m-63 = 0
\Rightarrow m =\frac{9}{7}, \frac{-7}{9}
Equation of line
(y-5) = \frac{-7}{9}(x-4)
(y-5) = \frac{9}{7}(x-4)