Gradient of parabola and specific max of y with 4 unknowns
i am needing help with a Maths equation that i cannot figure out. i need the gradient at x=45 to equal 3.21609 (y'=-25.593*cos(pi/25x - 4pi/5)). i also need the max of the parabola to equal (x,55) where x is unknown. a , b and c are not given. it is really bugging me because i have wasted about 20 pages and still cannot find it.
if i have missed something please ask me.
where y'=0, x=-B/2A and y=(-AB^2)/(4A^2)+C
therefore 55 + (AB^2)/(4A^2)=C
y = Ax^2 +BX +C
y'= 2Ax + B
therefore at x = 45
3.21609 - 90A=B
using these i altered the equations but got nowhere. is the problem there (equations) if anyone can help?