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Mumz [18]
3 years ago
10

If the area of a circle is 16pi what is the circumference of the circle, circle b, if its radius is 1/2 that of the circle a

Mathematics
1 answer:
Natasha2012 [34]3 years ago
5 0
First find the radius of circle A. You know that the equation is r^2*pi, so just divide both by pi.
r^2*pi=16pi
/pi          /pi
r^2=16
R is 4. That means that circle B is 2, since its radius is half that of circle A.
C=pi2r
C=pi2(2)
C=pi4
C=4pi
The answer is 4pi.
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The perimeter of equilateral triangle ABC is 81/3 centimeters, find the length of the radius and apothem.
MAXImum [283]

There is a typo error, the perimeter of equilateral triangle ABC is 81/√3 centimeters.

Answer:

Radius = OB= 27 cm

Apothem = 13.5 cm

A diagram is attached for reference.

Step-by-step explanation:

Given,

The perimeter of equilateral triangle ABC is 81/√3 centimeters.

Substituting this in the formula of perimeter of equilateral triangle =3\times\ side

3\times\ side =[tex]81\sqrt{3}

Side = \frac{81\sqrt{3} }{3} =27\sqrt{3} \ cm

Thus from the diagram , Side AB=BC=AC= 27\sqrt{3} \ cm

We know each angle of an equilateral triangle is 60°.

From the diagram, OB is an angle bisector.

Thus \angle OBC = 30°

Apothem is the line segment from the mid point of any side to the center the equilateral triangle.

Therefore considering ΔOBE, and applying tan function.

tan\theta =\frac{perpendicular}{base} \\tan\theta=\frac{OE}{BE} \\tan\theta=\frac{OE}{\frac{27\sqrt{3}}{2}  } \\tan30\times {\frac{27\sqrt{3} }{2} }= OE\\\frac{1}{\sqrt{3} } \times\frac{27\sqrt{3} }{2} =OE\\

Thus ,apothem  OE= 13.5 cm

Now for radius,

We consider ΔOBE

cos\theta=\frac{base}{hypotenuse} \\cos30= \frac{BE}{OB} \\Cos30 = \frac{\frac{27\sqrt{3} }{2}}{OB}  \\OB= \frac{\frac{27\sqrt{3} }{2}}{cos30} \\OB= \frac{\frac{27\sqrt{3} }{2}}{\frac{\sqrt{3} }{2} } \\OB =27 \ cm

Thus for

Perimeter of equilateral triangle ABC is 81/√3 centimeters,

The radius of equilateral triangle ABC is 27 cm

The apothem of equilateral triangle ABC is 13.5 cm

4 0
3 years ago
Somebody please help. And be fr cause I’ll give that brainilest or whatever it’s called but please be the right answer.
bearhunter [10]
130 you multiply the left side by 13 to get the right side.
8 0
2 years ago
I NEED IMMEDIATE HELP!!
DENIUS [597]

It A because the two mirror each other so you can simplify them to (3x−5)^2.

7 0
3 years ago
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Write an equation that represents the line
Savatey [412]

Answer:

y = -1/2 x - 3.5

Step-by-step explanation:

y = mx+ b

m is the slope of the line

m = -1/2

b is the y-intercept

b = -3.5

4 0
3 years ago
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Hi what is the answer
elena-s [515]

Answer:

a) y = 5x

b) y = 60

Step-by-step explanation:

We can see that when you multiply x by 5, you get the y value.

So, 12*5 = 60.

4 0
3 years ago
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