Find an Equation of the tangent line to the parabola at the given point and find the x-intercept of the line...
x^2=2y, (4,8)
I haven't learned derivatives yet. Can you solve it like this:
Find the y-intercept by equating the lenths of the two sides of the isosceles triangle formed by the tangent line and the y-axis. (d1 and d2).
I just don't know how to equate them...
and then for slope you would do the slope formula
let be the equation of the tangent line thru the point
equation of the parabola is
the tangent line and the parabola have equal y-values ...
since the tangent line touches the curve at a single point, the resulting quadratic has a single solution ... the discriminant must = 0
choose the positive slope
... now you have the slope of the tangent line and can finish whatever it is you need to do.