Answer:
Step-by-step explanation:
The standard equation of a parabola is
y² = 4ax
where, a is the focus,
The coordinates of the centre of parabola is (0,0)
coordinates of focus is (a, 0)
It is symmteric about the x axis
the equation of directrix is x = -a.
1/2 * ( 9 * 6 * 10)
1/2 * 540
270
20 is the father's 20 is the son
20+20=40
40/2=20
40-20=20
another way:
20:n= 40
20:20=40