Answer I think it is c I hope that right I am sorry for late responds
I believe it is the first one but I might be wrong.
When the triangle is a right triangle, you can use the Pythagorean theorem. The formula would be
c^2 = a^2 + b^2
If a = 21 and c=29, thus
b^2 = c^2 - a^2
b^2 = 29^2 - 21^2
b^2 = 400
b = square root (400)
b = 20 units.
Thus, the answer is <span>D) B = 400</span>
The function
exists in a parabola.
The axis of symmetry of a parabola exists at the midpoint between the two real roots.
The roots exist the solutions of H(t) = 0
To estimate the roots equation exists 
Factor t(-16t + 64) = 0
t = 0 and -16t + 64 =0
-16t + 64 = 0
t = 64 / 16 = 4
t = 4
Then the two roots are t = 0 and t = 4, and the axis of symmetry exists
t = (0+4)/2 = 4/2 = 2
<h3>How to estimate the axis of symmetry?</h3>
The axis of symmetry exists at t = 2.
It represents the time at which the ball is at the higher point, the maximum height.
You can find the maximum height replacing t = 2 in the function H(t)

= 64 feet.
And you can also deduce that the second part of the flight will take 2 seconds, for a total flight time of 4 seconds.
To learn more axis of symmetry refers to:
brainly.com/question/21191648
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