Originally posted by HanHao:
let the unknown point on the curve be (a,b)
since y = x^2
let the unknown point on the curve be (a,a^2)
use distance of 2 points formular
solve the quadratic equation
Your proposed solution is only half complete. Let me continue for u..
- Use distance between 2 pts formula, you would achieve a relation between the distance 'S' and the unknown 'a'.
- Differentiate S with respect to a
- Equate dS/da to zero
- Obtain the value of 'a' and thus the unknown point (a, a^2)
Second possible solution:
- Let unknown pt on the curve be (a, a^2)
- Find the expression of normal at the curve at (a, a^2)
- Equation of line for the normal at the curve at (a, a^2)
- Sub in x=3 and y=0 into the equation to obtain a, and hence the unknown point (a, a^2)
