\
The parabola is .
The both tangents to the parabola intersect on axis are orthogonal .
From the point of symmetry, the lines make angle of with positive and negative
axis respectively.
Therefore we can assume the points of tangency as and
.
Slope of the tangent line is derivative of the curve.
\Differentiate on each side with respect to .
Find the slope at .
.
Find the slope at .
.
The two tangents are perpendicular to each other,so the product of their slopes is .
Substitute above value in the points and
.
The points of tangency are and
.
Find the equation of tangent line :
Slope at :
.
Point -slope form of line equation: .
Substitute and point
in the above formula.
Find the equation of tangent line :
Slope at :
.
Point -slope form of line equation: .
Substitute and point
in the above formula.
Compare both tangent line equations with slope-intercept form .
intercepts of these two lines are
and
.
Thus the point of intersection on axis is
.
Graph:
\Graph of the parabola.
\Graph the tangent line equations.
\Observe the graphs.
\The tangent lines intersect on axis at
.
\
Graph of the parabola with tangents intersecting on axis.
.