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3 years ago

How many edges are there in an octahedron, a polyhedron with eight congruent triangular faces?

1 answer:

5 0

An octahedron in geometry is defined as a polyhedron with eight faces, six vertices and twelve edged. The term is used for regular octahedron mostly.
Thus we can summarize it as:
Number of edges: 12
Number of faces: 8
Number of faces: 6
the answer is 12 edges.

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PLEASE HELP I DO NOT UNDERSTAND AT ALL ITS PRECALC PLEASE SERIOUS ANSWERS

Elina [12.6K]

You want to end up with $A\sin(\omega t+\phi)$ . Expand this using the angle sum identity for sine:

$A\sin(\omega t+\phi)=A\sin(\omega t)\cos\phi+A\cos(\omega t)\sin\phi$

We want this to line up with $2\sin(4\pi t)+5\cos(4\pi t)$ . Right away, we know $\omega=4\pi$ .

We also need to have

$\begin{cases}A\cos\phi=2\\A\sin\phi=5\end{cases}$

Recall that $\sin^2x+\cos^2x=1$ for all $x$ ; this means

$(A\cos\phi)^2+(A\sin\phi)^2=2^2+5^2\implies A^2=29\implies A=\sqrt{29}$

Then

$\begin{cases}\cos\phi=\frac2{\sqrt{29}}\\\sin\phi=\frac5{\sqrt{29}}\end{cases}\implies\tan\phi=\dfrac{\sin\phi}{\cos\phi}=\dfrac52\implies\phi=\tan^{-1}\left(\dfrac52\right)$

So we end up with

$2\sin(4\pi t)+5\cos(4\pi t)=\sqrt{29}\sin\left(4\pi t+\tan^{-1}\left(\dfrac52\right)\right)$

8 0

3 years ago

Read 2 more answers

assume the graph of a function of the form y=asin(k(x+b)) is given below. which of the following are possible values for a, k, a

WITCHER [35]

Answer:

a=4, k=2, and b= -pi/4

Step-by-step explanation:

5 0

2 years ago

PLEASE HELP!!! 14 POINTS!

Pepsi [2]

Area=1/2bh

add them
(1/2)ab+(1/2)c^2+(1/2)ab=
ab+(1/2)c^2
ab+(1/2)(a^2+b^2)
not sure which option to pick there are different preferences on what counts as 'simplified'

4. find area
area=LW
area=105*45=4725
depends on the area of the signs
answer is
4725/(areaof1sign)
anyway, round down your answer because you will have an incomplete sign if you don't

5. area=pir^2
1/2 of it is
area=1/2pir^2
area=(1/4)^2pir^2
area=pi((1/4)r)^2
the radius is now 1/4 of what it was originally, meaning that the diameter is also 1/4 of what it is now
we need to know diamater
answer is 1/4 of current diameter

3. unclear

4. area of 1 sign not given, answer is 4725/(areaof1sign), rounded DOWN to nearest integer

5. (404 error, diameter not found) answer is 1/4 of current diameter

8 0

3 years ago

Write the equation of a circle whose center is at (-1,5) and radius is 8

labwork [276]

Answer:

X²+y²+2x-10y+18=0 is the equation of circle

Step-by-step explanation:

Eqn of circle is: (x-h) ²+(y-k)²=r²

At (h, k) =(-1,5) and r=8 where h, k are center and r is radius.

Eqn is :(x+1)²+(y-5)²=8²

Or, x²+2x+1+y²-10y+25=8

Or, x²+y²+2x-10y+18=0 is the equation of circle

6 0

2 years ago

The orange shape is a dilation of the black shape

grigory [225]

Answer:

1/4

Step-by-step explanation:

The orange shape is 3 units tall and 4 units wide. The black shape is 12 units tall and 16 units wide. The scale factor is ...

orange/black = 3/12 = 4/16 = 1/4

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7 0

2 years ago