CBSE Class 11-science Answered

Equation for pair of lines is

above expression is simplified as follows

x[ y - x cot(2α) ] = 0

From above expression , we get two equations that represent pair of lines

x= 0  ...................................(1)

y = x cot2α  ..............................(2)

Equation (1) is y-axis . If two lines are perpendicular to each other , then other line is x-axis .

Since equation of x-axis is y = 0 , then we get cot2α = 0   or  α = π/4

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