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3 years ago

Find the surface area of the cone radius 8 height 7 . Use 3.14 for pi. Explain everything.

Mathematics

1 answer:

Blizzard [7]3 years ago

6 0

Answer:

467.99 units²

Step-by-step explanation:

The formula for finding the surface area of a cone is:

$A=\pi r(r+\sqrt{h^{2}+r^{2}})$

Our values are:

r = 8

h = 7

π = 3.14

Let's plug the values into the formula

$A=\pi 8(8+\sqrt{7^{2}+8^{2}})$

$A=\pi 8(8+\sqrt{49+64})$

$A=\pi 8(8+\sqrt{113})$

$A=\pi 8(8+10.63)$

$A=\pi 8(18.63)$

$A= (3.14)(8)(18.63)$

$A= (25.12)(18.63)$

$A= 467.99$ units²

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from an observer o, the angles of elevation of the bottom and the top of a flagpole are 40° and 45° respectively.find the height

maksim [4K]

Answer:

Take a look of the image below, we can think on this problem as a problem of two triangle rectangles.

We can see that both triangles share the adjacent cathetus, then the height of the flagpole is just the difference between the opposite cathetus.

Remember the relation:

Tan(a) = (opposite cathetus)/(adjacent cathetus)

So, if we define H as the height of the cliff

X as the distance between the observer and the cliff

and h as the height of the flagopole

we can write:

tan(40°) = H/X

tan(45°) = (H + h)/X

Notice that we have two equations and 3 variables (we should have the same number of equations than variables) then here is missing information, and we can't get an exact solution for the height of the flagpole.

But we can write it in terms of the height of the cliff H, or in terms of the distance between the observer and the cliff.

We want to find the value of h.

If we take the quotient between both equations, we get:

Tan(45°)/Tan(40°) = (H + h)/H

1.192 = (H + h)/H

1.192*H = H + h

1.192*H - H = h

0.192*H = h

So the height of the flagpole is 0.192 times the height of the cliff.

6 0

3 years ago

What is 1-2sin^2x=sinx <br> Please show steps and find all solutions in interval [0,2pi)

Svetlanka [38]

Answer:

$\large\boxed{x=\dfrac{3\pi}{2}\ \vee\ x=\dfrac{\pi}{6}\ \vee\ x=\dfrac{5\pi}{6}}$

Step-by-step explanation:

$1-2\sin^2x=\sin x\\\\\text{substitute}\ t=\sin x,\ t\in[-1,\ 1]\\\\1-2t^2=t\qquad\text{subtract t from both sides}\\\\-2t^2-t+1=0\qquad\text{change the signs}\\\\2t^2+t-1=0\\\\2t^2+2t-t-1=0\\\\2t(t+1)-1(t+1)=0\\\\(t+1)(2t-1)=0\iff t+1=0\ \vee\ 2t-1=0\\\\t+1=0\qquad\text{subtract 1 from both sides}\\\boxed{t=-1}\\\\2t-1=0\qquad\text{add 1 to both sides}\\2t=1\qquad\text{divide both sides by 2}\\\boxed{t=\dfrac{1}{2}}$

$\sin x=-1\to x=-\dfrac{\pi}{2}+2k\pi,\ k\in\mathbb{Z}\\\\\sin x=\dfrac{1}{2}\to x=\dfrac{\pi}{6}+2k\pi\ \vee\ x=\dfrac{5\pi}{6}+2k\pi,\ k\in\mathbb{Z}\\\\x\in[0,\ 2\pi)$

$x=-\dfrac{\pi}{2}\notin[0,\ 2\pi)\\\\x=-\dfrac{\pi}{2}+2\pi=\dfrac{3\pi}{2}\in[0,\ 2\pi)\\\\x=-\dfrac{\pi}{2}+4\pi=\dfrac{7\pi}{2}\notin[0,\ 2\pi)\\\\x=\dfrac{\pi}{6}\in[0,\ 2\pi)\\\\x=\dfrac{\pi}{6}+2\pi=\dfrac{13\pi}{6}\notin[0,\ 2\pi)\\\\x=\dfrac{5\pi}{6}\in[0,\ 2\pi)\\\\x=\dfrac{5\pi}{6}+2\pi=\dfrac{17\pi}{6}\notin[0,\ 2\pi)$

4 0

3 years ago

PLZ HELP I WILL GIVE BRAINLIEST

Kipish [7]

Answer:

the third one

Step-by-step explanation:

bc like there are 2 boxes of 1 and 5 boxes of 1/6 so thats already 2 and 5/6 which applies to all of them. then there is 1 box of 1 and 2 boxes of 1/3 so thats 1 and 1/3 which applies to all of them also but when you make them have the same denominator you get 2 and 5/6 + 1 and 4/6 which deletes the second one. When you add you should get the same denominator so that deletes the first one so then you simplify that and the fraction should still be equal to the unsimplified fraction so you should get 4 and 1/2 if that makes sense

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3 years ago

What is the resulting equation when the expression for y in the second equation is substituted into the first equation?

Anni [7]

Answer: 3x + 6 -4x = 1

Simplify to -x + 6 = 1 because 3x - 4x = -1x

5 0

3 years ago

Florida has 8 less than 5 times the number of countries in Arizona

HACTEHA [7]

y = florida's number of countries x = countries in Arizona

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