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2 years ago

I’m confused :( I will mark as Brainliest and give you points

Mathematics

1 answer:

Ludmilka [50]2 years ago

8 0

Answer:

123.5 square inches

Step-by-step explanation:

Given: To find the area of a rectangle, you have to multiply base times height.

To find the area of a triangle, you have to do base times height devided by 2.

Finding the area: Let's break up this shape into polygons. At the bottom there is a rectangle. We know that to find the area of the rectangle you have to do base times height. 13in•7in will give you 91in square for the rectangle.

Now for the triangle. If you can see, if you break the triangle in half, there are 2 right triangles. Let's look at the right one for now. Since we know that to find the area of a triangle you have to do base times height divided by 2, you do 5in•6.5in=32.5in. 32.5in divided by 2 is 16.25in square which is the area of one triangle. You might be wondering why i did 5•6.5, and that's because at the bottom of the rectangle you can see it's 13in, and 13in÷2=6.5in.

We already found the area of the rectangle and one triangle. The other triangle is equal to it so we can just do 16.25+16.25=32.5in square for both of the triangles.

Now we add it all up: 32.5+91=123.5 square inches

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Answer:

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2 years ago

Using Euler’s formula, how many edges does a polyhedron with 20 faces and 12 vertices have?

astra-53 [7]

Euler's formula for a polyhedron is given by:

$\begin{gathered} F+V=E+2 \\ \text{where,} \\ F=\text{faces} \\ V=\text{vertices} \\ E=\text{edges} \end{gathered}$

Make E, the subject of the formula:

$\begin{gathered} F+V=E+2 \\ E=F+V-2 \end{gathered}$

Put F = 20, V = 12, to obtain E,

$\begin{gathered} E=20+12-2 \\ E=30 \end{gathered}$

Therefore, there are 30 edges

3 0

11 months ago

Solve the equation-27.5-m=21.1

ehidna [41]

Answer:

m=-48.6

Step-by-step explanation:

-27.5-m=21.1

m=-27.5-21.1

m=-48.6

8 0

3 years ago

Read 2 more answers

10. Two lighthouses are located on a north-south line.

Kamila [148]

The question is an illustration of bearing (i.e. angles) and distance (i.e. lengths)

The distance between both lighthouses is 5783.96 m

I've added an attachment that represents the scenario.

From the attachment, we have:

$\mathbf{\angle A = 180^o - 120^o\ 43'}$

Convert to degrees

$\mathbf{\angle A = 180^o - (120^o +\frac{43}{60}^o)}$

$\mathbf{\angle A = 180^o - (120^o +0.717^o)}$

$\mathbf{\angle A = 180^o - (120.717^o)}$

$\mathbf{\angle A = 59.283^o}$

$\mathbf{\angle B = 39^o43'}$

Convert to degrees

$\mathbf{\angle B = 39^o + \frac{43}{60}^o}$

$\mathbf{\angle B = 39^o + 0.717^o}$

$\mathbf{\angle B = 39.717^o}$

So, the measure of angle S is:

$\mathbf{\angle S = 180 - \angle A - \angle B}$ ---- Sum of angles in a triangle

$\mathbf{\angle S = 180 - 59.283 - 39.717}$

$\mathbf{\angle S = 81}$

The required distance is distance AB

This is calculated using the following sine formula:

$\mathbf{\frac{AB}{\sin(S)} = \frac{AS}{\sin(B)} }$

Where:

$\mathbf{AS = 3742}$

So, we have:

$\mathbf{\frac{AB}{\sin(81)} = \frac{3742}{\sin(39.717)}}$

Make AB the subject

$\mathbf{AB= \frac{3742}{\sin(39.717)} \times \sin(81)}$

$\mathbf{AB= 5783.96}$

Hence, the distance between both lighthouses is 5783.96 m

Read more about bearing and distance at:

brainly.com/question/19017345

5 0

2 years ago

A random sample of 20 students yielded a mean of ¯x = 72 and a variance of s2 = 16 for scores on a college placement test in mat

Helen [10]

Answer:

The 98% confidence interval for the variance in the pounds of impurities would be $8.400 \leq \sigma^2 \leq 39.827$ .

Step-by-step explanation:

1) Data given and notation

$s^2 =16$ represent the sample variance

s=4 represent the sample standard deviation

$\bar x$ represent the sample mean

n=20 the sample size

Confidence=98% or 0.98

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population mean or variance lies between an upper and lower interval".

The margin of error is the range of values below and above the sample statistic in a confidence interval.

The Chi square distribution is the distribution of the sum of squared standard normal deviates .

2) Calculating the confidence interval

The confidence interval for the population variance is given by the following formula:

$\frac{(n-1)s^2}{\chi^2_{\alpha/2}} \leq \sigma^2 \leq \frac{(n-1)s^2}{\chi^2_{1-\alpha/2}}$

On this case the sample variance is given and for the sample deviation is just the square root of the sample variance.

The next step would be calculate the critical values. First we need to calculate the degrees of freedom given by:

$df=n-1=20-1=19$

Since the Confidence is 0.98 or 98%, the value of $\alpha=0.02$ and $\alpha/2 =0.01$ , and we can use excel, a calculator or a table to find the critical values.