Answer:
R290.1
Step-by-step explanation:
Let
x = charge before he put his prices up
New charge = R320
Percentage increase in price = 7%
x + 7% of x = 320
x + 0.07 * x = 320
x + 0.07x = 320
1.07x = 320
x = 320/1.07
x = 299.06542056074
Approximately
x = R290.1
Charge before he put his prices up = R290.1
Split up the integration interval into 4 subintervals:
![\left[0,\dfrac\pi8\right],\left[\dfrac\pi8,\dfrac\pi4\right],\left[\dfrac\pi4,\dfrac{3\pi}8\right],\left[\dfrac{3\pi}8,\dfrac\pi2\right]](https://tex.z-dn.net/?f=%5Cleft%5B0%2C%5Cdfrac%5Cpi8%5Cright%5D%2C%5Cleft%5B%5Cdfrac%5Cpi8%2C%5Cdfrac%5Cpi4%5Cright%5D%2C%5Cleft%5B%5Cdfrac%5Cpi4%2C%5Cdfrac%7B3%5Cpi%7D8%5Cright%5D%2C%5Cleft%5B%5Cdfrac%7B3%5Cpi%7D8%2C%5Cdfrac%5Cpi2%5Cright%5D)
The left and right endpoints of the
-th subinterval, respectively, are


for
, and the respective midpoints are

We approximate the (signed) area under the curve over each subinterval by

so that

We approximate the area for each subinterval by

so that

We first interpolate the integrand over each subinterval by a quadratic polynomial
, where

so that

It so happens that the integral of
reduces nicely to the form you're probably more familiar with,

Then the integral is approximately

Compare these to the actual value of the integral, 3. I've included plots of the approximations below.
Answer: 60
Step-by-step explanation:
Just got the wrong answer to see what it was
Surface area = 2(12*12+15*12+15*12) = 1008
1008 * 4 = 4032
The answer would be 54, because A= PQ over 2 = 9 x 12 over 2 = 54