Answer: Rate of change of Area of the triangle = 2.75cm~/min
Step-by-step explanation:
If the present height of the triangle is 22cm and the height increases by 5cm/min. It means the height was 2cm four minutes earlier: 5cm for 1st min + 5cm for 2nd min + 5cm for 3rd min + 5cm for 4th min = 20cm after 4min.
Therefore height equals 22 - 20 = 2cm four minutes earlier.
Using the same four minutes for the base. Since the base shrinks at 1cm/min, for the base to shrink to 10cm it means it was 14cm four minutes earlier.
The Area of a triangle is given by
A = 1/2 × base × height
Therefore Area= 1/2× 10×22 = 110cm~
Since it took four minutes to get to this area, the rate of change of the area will be 110÷4 = 2.75cm~/min
to get the slope of any line, all we need is two points off of it, so let's get the slope and thus its equation, hmmmm let's see points (-2,-3) and the origin are the obvious ones =)
![\bf (\stackrel{x_1}{-2}~,~\stackrel{y_1}{-3})\qquad (\stackrel{x_2}{0}~,~\stackrel{y_2}{0}) \\\\\\ slope = m\implies \cfrac{\stackrel{rise}{ y_2- y_1}}{\stackrel{run}{ x_2- x_1}}\implies \cfrac{0-(-3)}{0-(-2)}\implies \cfrac{0+3}{0+2}\implies \cfrac{3}{2} \\\\\\ \begin{array}{|c|ll} \cline{1-1} \textit{point-slope form}\\ \cline{1-1} \\ y-y_1=m(x-x_1) \\\\ \cline{1-1} \end{array}\implies y-(-3)=\cfrac{3}{2}[x-(-2)]\implies y+3=\cfrac{3}{2}(x+2) \\\\\\ y+3=\cfrac{3}{2}x+3\implies y=\cfrac{3}{2}x](https://tex.z-dn.net/?f=%5Cbf%20%28%5Cstackrel%7Bx_1%7D%7B-2%7D~%2C~%5Cstackrel%7By_1%7D%7B-3%7D%29%5Cqquad%20%28%5Cstackrel%7Bx_2%7D%7B0%7D~%2C~%5Cstackrel%7By_2%7D%7B0%7D%29%20%5C%5C%5C%5C%5C%5C%20slope%20%3D%20m%5Cimplies%20%5Ccfrac%7B%5Cstackrel%7Brise%7D%7B%20y_2-%20y_1%7D%7D%7B%5Cstackrel%7Brun%7D%7B%20x_2-%20x_1%7D%7D%5Cimplies%20%5Ccfrac%7B0-%28-3%29%7D%7B0-%28-2%29%7D%5Cimplies%20%5Ccfrac%7B0%2B3%7D%7B0%2B2%7D%5Cimplies%20%5Ccfrac%7B3%7D%7B2%7D%20%5C%5C%5C%5C%5C%5C%20%5Cbegin%7Barray%7D%7B%7Cc%7Cll%7D%20%5Ccline%7B1-1%7D%20%5Ctextit%7Bpoint-slope%20form%7D%5C%5C%20%5Ccline%7B1-1%7D%20%5C%5C%20y-y_1%3Dm%28x-x_1%29%20%5C%5C%5C%5C%20%5Ccline%7B1-1%7D%20%5Cend%7Barray%7D%5Cimplies%20y-%28-3%29%3D%5Ccfrac%7B3%7D%7B2%7D%5Bx-%28-2%29%5D%5Cimplies%20y%2B3%3D%5Ccfrac%7B3%7D%7B2%7D%28x%2B2%29%20%5C%5C%5C%5C%5C%5C%20y%2B3%3D%5Ccfrac%7B3%7D%7B2%7Dx%2B3%5Cimplies%20y%3D%5Ccfrac%7B3%7D%7B2%7Dx)
Alright, lets get started.
The length of each section what carpenter needs to cut is 3 feet and 8 inches.
Converting 3 feet and 8 inches into feet only, we know, 
So, 3 feet 8 inches = 
feet
It means length of each section = 
feet
Carpenter needs to cut 4 sections, so length of 4 sections will be = 
2/3 feet means 8 inches so she needs board 14 feet 8 inches
Board is only sold by the feet only so, she has to puchase 15 feet board. : Answer
Hope it will help :)
So here, we are starting with two numbers: the original price, and the price after the percent increase.
First, we need to find the differences between the prices to figure out how much of a difference the percent made. $181.09 - $102.30 = $78.79
$78.79 is how much money the original price was increased by. We can find the percent change using this, since this number is what percent of the original price went up.
So now: $78.78 / $102.30 = .77018
And now, we convert that to percent: 77%
The markup was 77%.
