Answer:
<h2>2. Combining old and new observations.</h2>
Step-by-step explanation:
Through the passage, Nicholas Copernicus is introducing to the reader a new worlds, based on observations from the pass, and recent observations made by scientists. Basically, he's talking about a work where the reader is going to able to learn and be aware about the stars and planets movements in a way that no one could imagine before.
Copernicus specifically states that those observations are based on ancient and new data.
Therefore, the right answer is 2, because it's a combination of old and new observations.
To find this answer, take both sides of the equality and square them:
(√ײ)=9²
This gives you:
×=81
We effectively rewrite the equation as
In order for the LHS to be defined, we need to restrict 
, or 
. Now, the LHS will vanish when the numerator is 0, which happens for
This value is indeed smaller than 4, so the solution is 
.
Answer:
9 seconds
Step-by-step explanation:
d=-16t²+vt+h
The water level will be at 0 level (distance = 0)
0 = 16t² - 90t - 486
8t² - 45t - 243 = 0
(t - 9) (8t + 27) = 0
t = 9 or t = -27
since time should be a positive number, so t = 9 second
