Qt3D How to draw a curve through 3 given points

[Son Nguyen Ngoc]

Hi all,
I want to draw a curve through given 3 points. I intend to find quadratic equation 2 base on 3 given point, then find coordinates of other point by this quadratic equation 2. But making a quadratic equation 2 base on 3 given point is too hard for me. Do you have some suggestion?

Thanks.