BITSAT2015MathematicsApplication of DerivativesActual
The line which is parallel to X-axis and crosses the curve y= x at an angle of 45^ , is
Options
- Ax= 1 4
- By= 1 4
- Cy= 1 2
- Dy=1
Correct answer
C. y= 1 2
Step-by-step solution
Given equation of a line parallel to X-axis is y = k Given equation of the curve is y= x , On solving equation of line with the equation of curve, we get x=k² Thus the intersecting point is ( k ², k ) It is given that the line y = k intersect the curve y= x at an angle of / 4 . This means that the slope of the tangent to y = x at ( k ², k ) is ( 4 )= 1 array l ( dy dx )_ ( k ², k ) = 1 ( 1 2 x )_ ( k ², k ) = 1 k = 1 2 array