-π/2 < arctan(x) < π/2
So cos(π/2) < cos(arctan(x)) < cos(0)
0 < cos(arctan(x)) < 1
Answer:
see explanation
Step-by-step explanation:
Using the identity
tan²x = sec²x - 1
Consider left side
sec²x + tan²x
= sec²x + sec²x - 1
= 2sec²x - 1
= right side , thus verified
hope it helps
it says I can't send if it has less than 20 characters why?
For this case we have the following equation:

Where,
t: time
v: initial speed
s: initial height
Substituting values we have:

By the time the ball hits the ground we have:

From here, we clear the value of time:
Using the quadratic equation we have:

Doing the calculations we have:

Discarding the negative root, we have that the time is:
Answer:
it takes the ball to hit the floor about:
1.15 seconds