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2 years ago

The average of 21, 18, 16 and x is 20. what is the value of x?

Mathematics

2 answers:

Radda [10]2 years ago

5 0

Answer: 25

Step-by-step explanation:

21 + 18 +16 + X = 20×4

55 + X = 80

X = 80- 55

erastovalidia [21]2 years ago

3 0

Answer:

21.75

Step-by-step explanation:

21- 16 = 5

5/2 2.5

16 + 2.5 or 21 - 2.5

18.5 - 18 = .5

1/2 times 1/2 =

1/4

1/4 = .25

18.5 - .25 or 18 + .25

18.25

20 - 18.25 = 1.75

1.75 + 20

21.75

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ABCD is a rectangle. What is the value of x?

ankoles [38]

Answer:

Step-by-step explanation:

Use the pythagorean theorem

a² + b² = c²

a² + 63² = 65²

a² + 3969 = 4225

a² = 256

a = 16

x = 16 meters

7 0

3 years ago

Read 2 more answers

Prove that the triangle EDF is isosceles. Give reasons for your answer.

Gekata [30.6K]

Answer:

$\triangle EDF$ is isosceles.

Step-by-step explanation:

Please have a look at the attached figure.

We are given the following things:

$\angle EDF = y$

$\text{External }\angle DFG = 90 +\dfrac{y}{2}$

Let us try to find out $\angle E$ and $\angle DFE$ . After that we will compare them.

Finding  $\angle DFE$ :

Side EG is a straight line so $\angle GFE = 180$

$\angle GFE$ is sum of internal $\angle DFE$ and external $\angle DFG$

$\angle GFE = 180 = \angle DFE + \angle DFG\\\Rightarrow 180 = \angle DFE + (90+\dfrac{y}{2})\\\Rightarrow \angle DFE = 180 - 90 - \dfrac{y}{2}\\\Rightarrow \angle DFE = 90 - \dfrac{y}{2} ....... (1)$

Finding  $\angle E$ :

Property of external angle: External angle in a triangle is equal to the sum of two opposite internal angles of a triangle.

i.e. external $\angle DFG$ = $\angle E + \angle EDF$

$\Rightarrow 90+\dfrac{y}{2} = \angle E + y\\\Rightarrow \angle E = 90+\dfrac{y}{2} -y\\\Rightarrow \angle E = 90-\dfrac{y}{2} ....... (2)$

Comparing equations (1) and (2):

It can be clearly seen that:

$\angle DFE = \angle E =90-\dfrac{y}{2}$

The two angles of $\triangle EDF$ are equal hence $\triangle EDF$ is isosceles.

8 0

2 years ago

What is 3/4 ÷ 1/6? Please help !......

Reika [66]

Answer:

4 1/2

Step-by-step explanation:

Apply the fractions formula for division, to

3/4÷1/6

and solve

3/6x4/1

=18/4

Reduce by dividing both the numerator and denominator by the Greatest Common Factor GCF(18,4) = 2

18/24÷2/2=9/2

Convert to a mixed number using

long division for 9 ÷ 2 = 4R1, so

9/2=4 1/2

Therefore:

3/4÷1/6=4 1/2

4 0

2 years ago

Given that Cosecant (t) = negative StartFraction 13 Over 5 EndFraction for Pi less-than t less-than StartFraction 3 pi Over 2 En

Sergio [31]

Answer:

$\bold{cot(t) =\dfrac{12}{5}}$

Step-by-step explanation:

Given that:

$Cosec (t) = -\frac{13}5$

for $\pi < t < \frac{3 \pi}2$

That means, angle $t$ is in the 3rd quadrant.

To find:

Value of cot(t)

Solution:

First of all, let us recall what trigonometric ratios are positive and what trigonometric ratios are negative in 3rd quadrant.

In 3rd quadrant, tangent and cotangent are positive.

All other trigonometric ratios are negative.

Let us have a look at the following identity:

$cosec^2\theta -cot^2\theta =1$

here, $\theta =t$

So, $cosec^2t-cot^2t=1$

$\Rightarrow (-\dfrac{13}{5})^2-cot^2t=1\\\Rightarrow (\dfrac{169}{25})-cot^2t=1\\\Rightarrow \dfrac{169}{25}-1=cot^2t\\\Rightarrow \dfrac{169-25}{25}=cot^2t\\\Rightarrow \dfrac{144}{25}=cot^2t\\\Rightarrow cot(t)=\pm\sqrt{\dfrac{144}{25}}\\\Rightarrow cot(t)=\pm\dfrac{12}{5}$

But, angle $t$ is in 3rd quadrant, so value of

$\bold{cot(t) =\dfrac{12}{5}}$

4 0

2 years ago

At the deli, 2 turkey subs and 5 veggie subs cost $29. 4 turkey subs and 3 veggie subs cost

MrMuchimi

Answer:

4/9 of sales are veggie 5/9 are turkey

4/(4+5)=4/9

5/(4+5)= 5/9

4/9 x 27 = 12

5/9 x 27 = 15

12 veggie subs sold and

15 turkey subs sold

12+15=27 total sold

Step-by-step explanation:

3 0

2 years ago