Answer
7% . . ...................
Hello!
To find cosine, use the formula cos = adjacent / hypotenuse.
According to angle B, adjacent of angle B is side A, and the hypotenuse is side c because the hypotenuse is always opposite the right angle.
Therefore, the cosine of angle B is a/c.
The equation gives the height of the ball. That is, h is the height of the ball. t is the time. Since we are looking for the time at which the height is 8 (h=8), we need to set the equation equal to 8 and solve for t. We do this as follows:




This is a quadratic equation and as it is set equal to 0 we can solve it using the quadratic formula. That formula is:

You might recall seeing this as "x=..." but since our equation is in terms of t we use "t-=..."
In order to use the formula we need to identify a, b and c.
a = the coefficient (number in front of)

= 16.
b = the coefficient of t = -60
c = the constant (the number that is by itself) = 7
Substituting these into the quadratic formula gives us:



As we have "plus minus" (this is usually written in symbols with a plus sign over a minus sign) we split the equation in two and obtain:

and

So the height is 8 feet at t = 3.63 and t=.12
It should make sense that there are two times. The ball goes up, reaches it's highest height and then comes back down. As such the height will be 8 at some point on the way up and also at some point on the way down.
Answer:

Step-by-step explanation:
step 1
Find the area of the circle
The area of the circle is equal to

we have


substitute


step 2
we know that
The area of a circle subtends a central angle of 2π radians
so
using proportion
Find out the area of a sector with a central angle of 8 π/11 radians
