Hello,
Answer C
h(t)=0=-16t²+200==>t=3.53533...(s)
Answer:

And if we convert to megahertz we got:

Step-by-step explanation:
For any mechanical wave we have the following general relationship:

where:
v represent the speed of the wave = 299790000 m/s
represent the wavelength for the radio station
f represent the frequency of interest
If we solve for the frequency we got:

And replacing the values we got:

And if we convert to megahertz we got:

The image is attached.
Answer:
x = 16°
Step-by-step explanation:
Segment AB, segment DC and segment EC all intersect at point C.
Here, we are told angle DCE measures 148°.
This is a semi-circle, and the total angle of a semi-circle is 180°.
Which means, x+x+148 = 180
Solving for x, we have:
x+x+148 = 180
2x + 148 = 180
2x = 180 - 148
2x = 32

x = 16°
The value of x is 16°