So if 1/2 = 18 miles, we want to first find how many sets of 1/2 are in 21/2. We can just do this by dividing.
(21/2) / (1/2) = 21
So we know that there are 21 sets of 1/2 in 21/2, and since 1/2 and 18 are equal, we can say we know there are 21 sets of 18.
We can multiply to find this.
21 * 18 = 378
So two towns are 378 miles apart.
Answer:
option d. vertical opposite angle
F(x) = 18-x^2 is a parabola having vertex at (0, 18) and opening downwards.
g(x) = 2x^2-9 is a parabola having vertex at (0, -9) and opening upwards.
By symmetry, let the x-coordinates of the vertices of rectangle be x and -x => its width is 2x.
Height of the rectangle is y1 + y2, where y1 is the y-coordinate of the vertex on the parabola f and y2 is that of g.
=> Area, A
= 2x (y1 - y2)
= 2x (18 - x^2 - 2x^2 + 9)
= 2x (27 - 3x^2)
= 54x - 6x^3
For area to be maximum, dA/dx = 0 and d²A/dx² < 0
=> 54 - 18x^2 = 0
=> x = √3 (note: x = - √3 gives the x-coordinate of vertex in second and third quadrants)
d²A/dx² = - 36x < 0 for x = √3
=> maximum area
= 54(√3) - 6(√3)^3
= 54√3 - 18√3
= 36√3.
It’s the 3rd one hopefully this helps
