If a parabola has x-intercepts at 13 and -21, what is the x-coordinate of its vertex

-4

Step-by-step explanation:

To find the x-coordinate of the vertex of a parabola given its x-intercepts, find the average of the x-intercepts:

x-coordinate of the vertex = (where and are the x-intercepts)

Plug in the x-intercepts 13 and -21

Therefore, the x-coordinate of the vertex is -4.

I hope this helps!

for b its (t) and c its (d)

step-by-step explanation:

hope this !

step-by-step explanation:

d = distance between moon and sun, which in this problem is the hypotenuse of a right triangle.  

the distance y is the side opposite to angle x in the right triangle.   use the definition of the sine function from basic trigonometry.

sin(x) = y/d ⇒

d = y/sin(x)