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2 years ago

. An Olympic runner completed a 100-meter race with a time of 12.5 seconds. What was her average speed?

Mathematics

1 answer:

svet-max [94.6K]2 years ago

5 0

So you would do 100 divided by 12.5 and that equals 8. So the answer would be 8mph

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Fine length of BC on the following photo.

MrMuchimi

Answer:

$BC=4\sqrt{5}\ units$

Step-by-step explanation:

see the attached figure with letters to better understand the problem

step 1

In the right triangle ACD

Find the length side AC

Applying the Pythagorean Theorem

$AC^2=AD^2+DC^2$

substitute the given values

$AC^2=16^2+8^2$

$AC^2=320$

$AC=\sqrt{320}\ units$

simplify

$AC=8\sqrt{5}\ units$

step 2

In the right triangle ACD

Find the cosine of angle CAD

$cos(\angle CAD)=\frac{AD}{AC}$

substitute the given values

$cos(\angle CAD)=\frac{16}{8\sqrt{5}}$

$cos(\angle CAD)=\frac{2}{\sqrt{5}}$ ----> equation A

step 3

In the right triangle ABC

Find the cosine of angle BAC

$cos(\angle BAC)=\frac{AC}{AB}$

substitute the given values

$cos(\angle BAC)=\frac{8\sqrt{5}}{16+x}$ ----> equation B

step 4

Find the value of x

In this problem

$\angle CAD=\angle BAC$ ----> is the same angle

equate equation A and equation B

$\frac{8\sqrt{5}}{16+x}=\frac{2}{\sqrt{5}}$

solve for x

Multiply in cross

$(8\sqrt{5})(\sqrt{5})=(16+x)(2)\\\\40=32+2x\\\\2x=40-32\\\\2x=8\\\\x=4\ units$

$DB=4\ units$

step 5

Find the length of BC

In the right triangle BCD

Applying the Pythagorean Theorem

$BC^2=DC^2+DB^2$

substitute the given values

$BC^2=8^2+4^2$

$BC^2=80$

$BC=\sqrt{80}\ units$

simplify

$BC=4\sqrt{5}\ units$

7 0

2 years ago

-5 + 8 • -7 <br> help lols

iris [78.8K]

Answer:

Step-by-step explanation:

-5 + (8 x -7)

using PEMDAS, (8 x -7) = -56

so -5 + -56 = -61

5 0

3 years ago

In a circle with a radius of 3 ft, an arc is intercepted by a central angle of 2π3 radians. What is the length of the arc?

madreJ [45]

The correct question is
<span>In a circle with a radius of 3 ft, an arc is intercepted by a central angle of 2π/3 radians. What is the length of the arc?

we know that
in a circle
</span>2π radians -----------------> lenght of (2*π*r)
2π/3 radians--------------> X
X=[(2π/3)*(2π*r)]/[2π]=(2π/3)*r

the lenght of the arc=(2π/3)*3=2π ft

the answer is 2π ft

5 0

3 years ago

Read 2 more answers

Which of the following is equivalent to 2:1

Len [333]

Answer:

use m a t h w a y

Step-by-step explanation:

put it all together and they will give you opitions

7 0

3 years ago

Read 2 more answers