What is the area of an equilateral triangle having side 'a' units?
​

Answer:

[tex]A=\frac{\sqrt{3}}{4}a^2[/tex]

Step-by-step explanation:

Since an equilateral has all of the sides equal, we can find the height of triangle using: [tex]a^2+b^2=c^2[/tex]. I attached a diagram which should explain how I got the dimensions of the three sides. Using the information from the diagram we get the equation:

[tex]h^2+(\frac{a}{2})^2=a^2[/tex]

Subtract a^2 from both sides

[tex]h^2=a^2-(\frac{a}{2})^2[/tex]

Take the square root of both sides

[tex]h = \sqrt{a^2-(\frac{a}{2})^2}[/tex]

If you know the area of a triangle, it's: [tex]\frac{1}{2}bh[/tex]. In this case the base=a, and the height is what we defined above. Using this we get:

[tex]A = \frac{a}{2}*\sqrt{a^2-(\frac{a}{2})^2}[/tex]

We can distribute the exponent over the division to get:
[tex]A = \frac{a}{2}*\sqrt{a^2-(\frac{a^2}{4})[/tex]

Now we can rewrite a^2 as 4a^2/4

[tex]A = \frac{a}{2}*\sqrt{\frac{4a^2}{4}-(\frac{a^2}{4})[/tex]

Now add the two fractions:

[tex]A = \frac{a}{2}*\sqrt{\frac{3a^2}{4}[/tex]

We can distribute the square root the division just like how we distributed the exponent 2, since the square root can be expressed as an exponent (1/2)

[tex]A = \frac{a}{2}*\frac{\sqrt{3a^2}}{\sqrt{4}}[/tex]

There's a radical identity that states: [tex]\sqrt[n]{a} * \sqrt[n]{b} = \sqrt[n]{a*b}[/tex]. We can use this to rewrite one radical as multiple radicals to simplify it:

[tex]A = \frac{a}{2}*\frac{\sqrt{a^2}*\sqrt{3}}{2}[/tex]

Simplify:

[tex]A = \frac{a}{2}*\frac{a*\sqrt{3}}{2}[/tex]

Now multiply the two fractions

[tex]A = \frac{a^2*\sqrt{3}}{4}[/tex]

This is the formula for the area of an equilateral triangle, but it is also often written as:
[tex]A=\frac{\sqrt{3}}{4}a^2[/tex]

Troy and Lisa were shopping for school supplies. Troy bought 3 notebooks and 5 thumb drives for $20.25. Lisa bought 8 notebooks and 8 thumb drives for $38. Find the cost of each notebook and the cost of each thumb drive.

An underground aquifer near Seiling, Oklahoma, sits on an impermeable layer of limestone. West of Seiling the limestone layer is thought to slope downward in a straight line. In order to map the limestone layer, hydrologists started at Seiling heading west and drilled sample wells. Two miles west of Seiling the limestone layer was found at a depth of 220 feet. Three miles west of Seiling the limestone layer was found at a depth of 270 feet
(a) What would you expect to be the depth of the limestone layer 5 miles west of Seiling
(b) You want to drill a well down to the limestone layer as far west from Seiling as you can. Your budget will allow you to drill a well that is 275 feet deep. How far west of Seiling can you go to drill the well? (Round your answer to one decimal place.)

How to do this problem? Thank you!

- 3x + 5y = -2
2x - 2y = 1
Solve by elem inaction

A new animal hospital is planning to purchase a total of 36 cages for dogs, cats, and
rabbits. They want to purchase the same number of cages for dogs as for cats, but only
one-fourth as many cages for rabbits. How many of each cage should they buy?

you want branliest.more branliest giving out

The flower shop has 40 times as many flowers in the cooler as Kendall has in her bouquet. Kendall has 15 flowers. How many flowers are in the cooler?

Can anyone help me thank you

The volume Vof a cylindrical can is represented by the formula V=πr2h, where h is the height and r is the radius. A cylindrical can has a volume of 1014π cubic centimeters and a height of 6 centimeters. What is the radius of the can?

Divide. Then, check your work with multiplication. 12.21 / 11

Si un ladrillo de adobe pesa 20kg. mas de la mitad de su peso. ¿Cuanto pesara un ladrillo y medio?​

PLEASE HELP ASAP I WILL GIVE YOU BRAINIEST!! Marcus is 14 years younger than twice Kimi's age. Marcus is 8 years old. How old is Kimi?

A researcher is conducting a study of charitable donations by surveying a simple random sample of households in a certain city. The researcher wants to determine whether there is convincing statistical evidence that more than 50 percent of households in the city gave a charitable donation in the past year. Let p represent the proportion of all households in the city that gave a charitable donation in the past year. Which of the following are appropriate hypotheses for the researcher?

a. H_o : p=0.5 and H_a:p>0.5
b. H_o:p=0.5 and H_a:p≠0.5
c. H_o:p=0.5 and H_a:p<0.5
d. H_o:p>0.5 and H_a:p≠0.5
e. H_o:p>0.5 and H_a:p=0.5

Dave has $70 saved and earns $20
each month in allowance. Terri has
$110 saved and earns $16 a month
in allowance. If they both save their
entire allowances, how long will it
take before Dave and Terri have saved
the same amount of money?

3629 you can use the digits twice make the largest four digit number​

Help
Please ..................

Guys I suck at this stuff so can someone Just PLEASE HELP ME

a. Solve for x in the
diagram

what is 893 :9 in long division​

23:
-
Determine the x- and y- intercepts for the graph defined by the given equation.
y = 7x + 3
a. X-intercept is (3,0)
CH
x-intercept is 0.-
y-intercept is 0,-
y-intercept is (3,0)
b.
d. x-intercept is (3, 0)
x-intercept is
0
y-intercept is
10
y-intercept is (0,3)
Please select the best answer from the choices provided
А
ОВ

An economist conducts a nationwide survey to study the financial perceptions of US adults. Specifically, he asks a random sample of 1,000 US adults: “Financially, are you doing OK or are you struggling to get by?” The results of the survey show that 829 of the 1,000 participants said they are doing OK.

(a) Construct a 95% confidence interval for the proportion of US adults who would say they are doing OK.

(b) Shortly thereafter, a similar study is conducted in Mexico with the intention of constructing a 95% confidence interval for the proportion of Mexican adults who would say they are doing OK. What is the smallest sample size that can be used to guarantee that the margin of error will be less than or equal to 0.01?

1.) Some banks charge a fee on savings accounts that are left inactive for an extended period of time. The equation y = 5000 * (0.98) ^ x represents the value, y of one account that was left inactive for a period of x years .

a. What was the initial amount of money that was left in this savings account?

b. What is the percent of change each year in this savings account?

Five higschool friends all happen to be female born in 2003 assuming that the survival of each ine is independent what is the proablity that at least one lives to be 100 year old

Which of the following is most likely the next step in the series?

Seven times a certain number plus the number is equal to 88. Find the number.

best answer gets brainliest​

Evaluate the following: a. 4|−8| b. 2|−3| + 4(7) c. 8|−2| − 6 d. 5|−4| + 2|−6|

I need help so please be nice and help me hurry cause I have to turn this in!!

2x +5y = -7
7x + y = -8
Solve by substitution SHOW WORK!

help asap, i will mark brainliest!

A. X = -6 and X = -5.5
B. x = -0.5 and x = -5
C. X = 0 and x = 5
D. X = 5 and x = 6