Найти [latex]\frac{d^2y}{dx^2}[/latex] функции [latex]\left \{ {{x=3(t-sint)} \atop {y=4(1-cost})} \right.[/latex]

[latex]x=\phi (t);\\ y=\psi (t);\\ y'_x=\frac{\psi'(t)}{\phi'(t)};\\ y''_{x^2}=\frac{\psi''(t)\phi '(t)-\psi'(t)\phi''(t)}{(\phi'(t))^3}[/latex]   [latex]x'_t=3-3cost;\\ x''_{t^2}=3sint;\\ y'_t=4sint;\\ y''_{t^2}=4cost;[/latex]   [latex]y''_{x^2}=\frac{4cost(3-3cost)-4sint *3sint}{(3-3cost)^3}=\\ \frac{12cost-12(cos^2 t+sin^2 t)}{27(1-cost)^3}=\\ \frac{12cost-12*1}{27(1-cost)^3}=\\ \frac{-12(1-cost)}{27(1-cost)^3}=\\ \frac{-4}{9(1-cost)^2}[/latex]