The equation for a parabola with directrix y = –p and focus (0, p)
The distance between vertex and directrix is P
Also the distance between vertex and focus is also P
Focus (0,p) so focus lies on y axis
Directrix line is paralled to focus point
So Directex crosses the x axis .
Hence line of symmetry lies is the y-axis.
The graph is attached below.
C
Use the formula of the Pythagorean theorem. a^2 + b^2 = c^2
a = 11.5
b = 18
11.5^2 + 18^2 = 456.25^2
Sqrt(456.25) to find c
c=21.36 in.
You're correct dear. Good Job.
9y is the answer I believe
Answer: 4 seconds
Step-by-step explanation:
Given: The function
can be used to model the height of the ball where t is the time in seconds after the ball kicked and h(t) is the height in feet.
Differentiate the given function with respect to t , we get

Put h'(t)=0

Also, 
By second derivative test, h(t) is maximum at t=4.
Hence, the time in Devon which the ball reaches it maximum height = 4 seconds