Question
If the lines 3x - 4y + 4 = 0 and 6x - 8y - 7 = 0 are tangents to a circle, then find the radius of the circle.
✓
Answer
Slope of 3x - 4y + 4 = 0 is $\frac{4}{3}$ Slope of 6x - 8y -7 = 0 is $\frac{8}{6}=\frac{4}{3}$ Slope of 3x - 4y + 4 = 0 and 6x - 8y - 7 = 0 are same. Hence two lines are parallel and are shown in figure. 
Rewriting 6x - 8y - 7 = 0, we get, $\Bigg|\frac{4+\frac{7}{2}}{\sqrt{9+16}}\Bigg|$ $\Big|\frac{15}{10}\Big|$ $=\frac{3}{4}$ Units
Rewriting 6x - 8y - 7 = 0, we get, $\Bigg|\frac{4+\frac{7}{2}}{\sqrt{9+16}}\Bigg|$ $\Big|\frac{15}{10}\Big|$ $=\frac{3}{4}$ UnitsNeed a full question paper?
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