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3 years ago

9

You’re given three angle measurements of 30°, 70°, and 80°. How many triangles can you construct using these measurements?

1 answer:

Katyanochek1 [597]3 years ago

6 0

Only one cause it takes 180 degrees<span> to make a triangle so all you do is add it up</span>

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Pls help ill mark brainliest

Andrei [34K]

Answer: 1 and 2/3

Step-by-step explanation:

since 1/5 goes to 1 it is multiplied by 5

so 1/3 times 5 is 1 and 2/3

8 0

2 years ago

Find the general solution of the equation: (y^2-2xy)dx + (2xy-x^2)dy = 0

lys-0071 [83]

The ODE is exact, since

$\dfrac{\partial(y^2-2xy)}{\partial y}=2y-2x$

$\dfrac{\partial(2xy-x^2)}{\partial x}=2y-2x$

so there is solution $f(x,y)=C$ such that

$\dfrac{\partial f}{\partial x}=y^2-2xy$

$\dfrac{\partial f}{\partial y}=2xy-x^2$

Integrating both sides of the first PDE wrt $x$ gives

$f(x,y)=xy^2-x^2y+g(y)$

Differentiating both sides wrt $y$ gives

$\dfrac{\partial f}{\partial y}=2xy-x^2+\dfrac{\mathrm dg}{\mathrm dy}=2xy-x^2$

$\implies\dfrac{\mathrm dg}{\mathrm dy}=0\implies g(y)=C$

Then the solution to the ODE is

$f(x,y)=\boxed{xy^2-x^2y=C}$

# # #

Alternatively, we can see that the ODE is homogeneous, since replacing $x\to tx$ and $y\to ty$ reduces to the same ODE:

$((ty)^2-2(tx)(ty))\,\mathrm d(tx)+(2(tx)(ty)-(tx)^2)\,\mathrm d(ty)=0$

$t^3(y^2-2xy)\,\mathrm dx+t^3(2xy-x^2)\,\mathrm dy=0$

$(y^2-2xy)\,\mathrm dx+(2xy-x^2)\,\mathrm dy=0$

This tells us we can solve by substituting $y(x)=xv(x)$ , so that $\mathrm dy(x)=x\,\mathrm dv(x)+v(x)\,\mathrm dx$ , and the ODE becomes

$(x^2v^2-2x^2v)\,\mathrm dx+(2x^2v-x^2)(x\,\mathrm dv+v\,\mathrm dx)=0$

$v(v-2)\,\mathrm dx+(2v-1)(x\,\mathrm dv+v\,\mathrm dx)=0$

$3v(v-1)\,\mathrm dx+x(2v-1)\,\mathrm dv=0$

which is separable as

$\dfrac{1-2v}{3v(v-1)}\,\mathrm dv=\dfrac{\mathrm dx}x$

Integrating both sides gives

$-\dfrac13\ln|v(1-v)|=\ln|x|+C$

$v(1-v)=\dfrac C{x^3}$

and solving in terms of $y(x)$ ,

$\dfrac yx\left(1-\dfrac yx\right)=\dfrac C{x^3}$

$xy(x-y)=C$

$\boxed{x^2y-xy^2=C}$

6 0

3 years ago

If 1 adult female is randomly selected, find the probability that her pulse rate is less than 76 beats per minute.

Anastaziya [24]

75/76 beats per minute, I think. Sorry if i'm wrong

6 0

3 years ago

How you multiply fractions?

viva [34]

you keep them how they are but put them side by side

for example multiply 2/9* 3/2 you will get 6/18 then simplify if needed, 3/9, 1/3

3 0

3 years ago

Slav-nsk [51]

Y = x – 6
x = –4
plug in x
y=-4-6
y=-4+-6
y=-10
(-4,-10)
this should be the solution

3 0

3 years ago

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