def task_1(self):
        """Первое задание"""
        self.ui.MainMenu.setCurrentIndex(1)
        fig = Figure(figsize=(5, 5))
        can = FigureCanvasQTAgg(fig)
        layout = QtWidgets.QVBoxLayout(self.ui.graphic)
        layout.addWidget(can)

        # here you can set up your figure/axis
        ax = can.figure.add_subplot(111)

        # plot a basic line plot from x and y values.
        ax.cla()  # clears the axis
        x = np.arange(-10, 10, 0.1)
        y = np.cos(x) * np.cos(x) * np.cos(x) * np.sin(x)
        for i in range(0, len(y)):
            y[i] = y[i] - (5 * x[i]) / (np.sin(2 * x[i]) * np.cos(x[i]))

        ax.plot(x, y)
        ax.grid(True)
        can.figure.tight_layout()
        can.draw()