# when i change parameters of parabula it make point on the graf undefined

vitaly shared this problem 8 months ago
Not a Problem

i want check area of triangle witch limited by parabola and axis X. for that i build my triangle by putting one dot on the parabola and 2 on axis x. to make it more flexible i drew parabola by using this formula " ax^2+bx+x " the problem begin if i change parameter a from positive to negative and visa versa. after the change it say the point (C in my program) undefined, until i press the function rectangle in the left area and then the point rectangle there. same happen if i change a value again.

p.s. if i don't limit the parabola between the points it intersect with axis X it don't have such problems

p.s.2 it seem the problem is caused because when putting point on graph the point keeps its axis x position while graph changes

1

You totally alters the function, when you only negates a.

If you wants to flip the parabola, you can negate the whole function.

1

Parabola may not intersect xAxis. If you need parabola to always intersect xAxis, you may use "a * ( x - x(A) ) * ( x - x(B) )".

1

i want that anyone who opens my simulation can enter the parameters of his parabola and if it intersect xAxis you can see what is max area of triangle witch inscribed by parabola and xAxis. if you open the file i added and play with parameters you can easily see the problem.

1

You have better stay with negative a-values, and use rulers for all the parameters.

Take a look at my attached file.