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2 years ago

Make cos C the subject of the formula C?= a? + b? - 2ab cos C

Mathematics

1 answer:

lara31 [8.8K]2 years ago

5 0

<h3>Answer: Choice E</h3>

Work Shown:

$c^2 = a^2 + b^2 - 2ab\cos(C)\\\\c^2 + 2ab\cos(C) = a^2 + b^2\\\\2ab\cos(C) = a^2 + b^2 - c^2\\\\\boldsymbol{\cos(C) = \frac{a^2 + b^2 - c^2}{2ab}}\\\\$

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PLEASE ANSWER ASAP FOR BRAINLEST!!!!!!!!!!!!!!!!

ANTONII [103]

Step-by-step explanation:

the answer for that question is letter D

7 0

3 years ago

Read 2 more answers

Let f(x,y,z) = ztan-1(y2) i + z3ln(x2 + 1) j + z k. find the flux of f across the part of the paraboloid x2 + y2 + z = 3 that li

Sophie [7]

Consider the closed region $V$ bounded simultaneously by the paraboloid and plane, jointly denoted $S$ . By the divergence theorem,

$\displaystyle\iint_S\mathbf f(x,y,z)\cdot\mathrm dS=\iiint_V\nabla\cdot\mathbf f(x,y,z)\,\mathrm dV$

And since we have

$\nabla\cdot\mathbf f(x,y,z)=1$

the volume integral will be much easier to compute. Converting to cylindrical coordinates, we have

$\displaystyle\iiint_V\nabla\cdot\mathbf f(x,y,z)\,\mathrm dV=\iiint_V\mathrm dV$
$=\displaystyle\int_{\theta=0}^{\theta=2\pi}\int_{r=0}^{r=1}\int_{z=2}^{z=3-r^2}r\,\mathrm dz\,\mathrm dr\,\mathrm d\theta$
$=\displaystyle2\pi\int_{r=0}^{r=1}r(3-r^2-2)\,\mathrm dr$
$=\dfrac\pi2$

Then the integral over the paraboloid would be the difference of the integral over the total surface and the integral over the disk. Denoting the disk by $D$ , we have

$\displaystyle\iint_{S-D}\mathbf f\cdot\mathrm dS=\frac\pi2-\iint_D\mathbf f\cdot\mathrm dS$

Parameterize $D$ by

$\mathbf s(u,v)=u\cos v\,\mathbf i+u\sin v\,\mathbf j+2\,\mathbf k$
$\implies\mathbf s_u\times\mathbf s_v=u\,\mathbf k$

which would give a unit normal vector of $\mathbf k$ . However, the divergence theorem requires that the closed surface $S$ be oriented with outward-pointing normal vectors, which means we should instead use $\mathbf s_v\times\mathbf s_u=-u\,\mathbf k$ .

Now,

$\displaystyle\iint_D\mathbf f\cdot\mathrm dS=\int_{u=0}^{u=1}\int_{v=0}^{v=2\pi}\mathbf f(x(u,v),y(u,v),z(u,v))\cdot(-u\,\mathbf k)\,\mathrm dv\,\mathrm du$
$=\displaystyle-4\pi\int_{u=0}^{u=1}u\,\mathrm du$
$=-2\pi$

So, the flux over the paraboloid alone is

$\displaystyle\iint_{S-D}\mathbf f\cdot\mathrm dS=\frac\pi2-(-2\pi)=\dfrac{5\pi}2$

6 0

3 years ago

Use the x-intercept method to find all real solutions of the equation.<br> x^3-8x^2+9x+18=0

meriva

Answer:

a. $x=-1,3,\:or\:6$

Step-by-step explanation:

The given equation is;

$x^3-8x^2+9x+18=0$

To solve by the x-intercept method we need to graph the corresponding function using a graphing calculator or software.

The corresponding function is

$f(x)=x^3-8x^2+9x+18$

The solution to $x^3-8x^2+9x+18=0$ is where the graph touches the x-axis.

We can see from the graph that; the x-intercepts are;

(-1,0),(3,0) and (6,0).

Therefore the real solutions are:

$x=-1,3,\:or\:6$

8 0

3 years ago

Read 2 more answers

Worth 60 points! First two options are Can/cannon and the last two options are identical/somewhat similar/similar/different

kotykmax [81]

Where are they I answered

4 0

3 years ago

Round to the nearest hundredth 42.052

Vera_Pavlovna [14]

42.052

place value and digits:

4 = tens
2 = ones
0 = tenths
5 = hundredths
2 = thousandths

5 is in the hundredths place. To find if you round up or down, look at the digit to the right (thousandths in this case). It is a 2, which is less than 5, so you round down.

42.052 rounded to the nearest hundredth is 42.05

hope this helps

8 0

3 years ago