Answer:
9
Step-by-step explanation:
The equation graphed from these points is y=3x+9, therefore the y-intercept is 9.
Answer:
The area of the rectangle is increasing at a rate of 84 square centimeters per second.
Step-by-step explanation:
The area for a rectangle is given by the formula:

Where <em>w</em> is the width and <em>l</em> is the length.
We are given that the length of the rectangle is increasing at a rate of 6 cm/s and that the width is increasing at a rate of 5 cm/s. In other words, dl/dt = 6 and dw/dt = 5.
First, differentiate the equation with respect to <em>t</em>, where <em>w</em> and <em>l</em> are both functions of <em>t: </em>
![\displaystyle \frac{dA}{dt}=\frac{d}{dt}\left[w\ell]](https://tex.z-dn.net/?f=%5Cdisplaystyle%20%5Cfrac%7BdA%7D%7Bdt%7D%3D%5Cfrac%7Bd%7D%7Bdt%7D%5Cleft%5Bw%5Cell%5D)
By the Product Rule:

Since we know that dl/dt = 6 and that dw/dt = 5:

We want to find the rate at which the area is increasing when the length is 12 cm and the width is 4 cm. Substitute:

The area of the rectangle is increasing at a rate of 84 square centimeters per second.
Answer:
The perimeter of a circle can be found by using the followinfg expression
P = 2*π*r
where
π = 3.14
r = radius of the circle = half the diameter of the circle
In this case, if we are given the radius, we use
P = 2*π*r
If we are given the diameter, we use
P = 2*π*(D/2) = π*D
1) 27in
radius = 27in
P = 2*(3.14)*(27 in) = 169.56 in
diameter = 27 in
P = (3.14)*(27 in) = 84.78 in
2) 79 in
radius = 79 in
P = 2*(3.14)*(79 in) = 496.12 in
diameter = 79 in
P = (3.14)*(79 in) = 248.06 in
3) 1809 in
radius = 1809 in
P = 2*(3.14)*(1809 in) = 11360.52 in
diameter = 1809 in
P = (3.14)*(1809 in) = 5680.26 in
4) 152 in
radius = 152 in
P = 2*(3.14)*(152 in) = 954.56 in
diameter = 152 in
P = (3.14)*(152 in) = 477.28 in