The segments of the focal chord PSQ of a parabola are the roots of the equation <img alt="\mathrm{2 x^{2}-17 x+7=0}" src="https://entrancecorner.oncodecogs.com/gif.latex?%5Cmathrm%7B2%20x%5E%7B2%7D
The segments of the focal chord PSQ of a parabola are the roots of the equation .Then the distance between tangent at vertex and directrix of the parabola is