Answer:
Step-by-step explanation:
Assume the dish opens upwards. The cross-section through the vertex is a parabola. You know three points on the parabola: (0,0), (2,2), and (-2,2). Plug the points into y = ax² + bx + c to get a system of three equations where a=0.5, b=c=0.
Equation of parabola: y = 0.5x²
:::::
Vertex (0,0)
Focal length = 1/(4×0.5) = 0.5
Focus (0,0+0.5) = (0, 0.5)
Directrix y = 0-0.5 = -0.5
:::::
At endpoints of latus rectum, y = 0.5
x = ±√0.5 = ±√2/2
Focal width = 2×√2/2 = √2
:::::
Place antenna at focus, (9,2)
