What is the surface area of the square pyramid?

Mathematics

1 answer:

wel2 years ago

3 0

Ok to start you need to break this into a net in your head. Next, calculate each triangle
(6*7)/2 = 21
Then, multiply each triangle by the amount of them.
21*4 = 84
Next, get the area of the square.
7*7 = 49
Lastly, add the triangles and the square up.
49 + 84 = 133

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Let f be defined by the function f(x) = 1/(x^2+9)

riadik2000 [5.3K]

(a)

$\displaystyle\int_3^\infty \frac{\mathrm dx}{x^2+9}=\lim_{b\to\infty}\int_{x=3}^{x=b}\frac{\mathrm dx}{x^2+9}$

Substitute x = 3 tan(t ) and dx = 3 sec²(t ) dt :

$\displaystyle\lim_{b\to\infty}\int_{t=\arctan(1)}^{t=\arctan\left(\frac b3\right)}\frac{3\sec^2(t)}{(3\tan(t))^2+9}\,\mathrm dt=\frac13\lim_{b\to\infty}\int_{t=\arctan(1)}^{t=\arctan\left(\frac b3\right)}\mathrm dt$

$=\displaystyle \frac13 \lim_{b\to\infty}\left(\arctan\left(\frac b3\right)-\arctan(1)\right)=\boxed{\dfrac\pi{12}}$

(b) The series

$\displaystyle \sum_{n=3}^\infty \frac1{n^2+9}$

converges by comparison to the convergent p-series,

$\displaystyle\sum_{n=3}^\infty\frac1{n^2}$

$\displaystyle \sum_{n=1}^\infty \frac{(-1)^n (n^2+9)}{e^n}$

converges absolutely, since

$\displaystyle \sum_{n=1}^\infty \left|\frac{(-1)^n (n^2+9)}{e^n}\right|=\sum_{n=1}^\infty \frac{n^2+9}{e^n} < \sum_{n=1}^\infty \frac{n^2}{e^n} < \sum_{n=1}^\infty \frac1{e^n}=\frac1{e-1}$

That is, ∑ (-1)ⁿ (n ² + 9)/eⁿ converges absolutely because ∑ |(-1)ⁿ (n ² + 9)/eⁿ| = ∑ (n ² + 9)/eⁿ in turn converges by comparison to a geometric series.

5 0

2 years ago

The point A(–1, 4) is translated five units right and three units down. Which rule describes the translation?

lozanna [386]

Answer: SECOND OPTION.

Step-by-step explanation:

Given the following point identified as "A":

$A(-1,4)$

You can identify that the x-coordinate of the point is:

$x=-1$

And its y-coordinate is:

$y=4$

According to the exercise, this point is translated five units right and three units down. This means that, in order to find the new coordinates, you need to add 5 to the original x-coordinate and subtract 3 from the original y-coordinate.

Therefore, you can conclude that the rule that best describe the translation of the point $A(-1,4)$ is the following:

$(x,y)$ → $(x+5,y-3)$