A square has a side length of 18 centimeters what is it’s perimeter

Mathematics

1 answer:

NARA [144]3 years ago

3 0

The perimeter is 72 because all sides on a square are the same measurements so you just have to do 18 times 4 to get 72

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this is formula manipulation, I'd appreciate if the steps were provided. only respond if you know how to get the answer, thank y

marissa [1.9K]

Answer:

r = 3V/(2πh²)
h = 3V/b²
r = 25/π cm ≈ 7.9577 cm
w = 15 cm

Step-by-step explanation:

1. Multiply both sides of the equation by the reciprocal of the coefficient of r.

$V\cdot\dfrac{3}{2\pi h^2}=r\\\\r=\dfrac{3V}{2\pi h^2}$

2. Multiply both sides of the equation by the reciprocal of the coefficient of h.

$V\cdot\dfrac{3}{b^2}=h\\\\h=\dfrac{3V}{b^2}$

3. Solve the circumference formula for r, then substitute the given information.

$C=2\pi r\\\\r=\dfrac{C}{2\pi}\qquad\text{divide by the coefficient of r}\\\\r=\dfrac{50\,\text{cm}}{2\pi}=\dfrac{25}{\pi}\,\text{cm}\approx 7.9577\,\text{cm}$

4. Solve the perimeter formula for width, the substitute the given information and do the arithmetic.

$P=2(L+W)\\\\\dfrac{P}{2}=L+W\qquad\text{divide by 2}\\\\\dfrac{P}{2}-L=W\qquad\text{subtract L}\\\\\dfrac{40\,\text{cm}}{2}-5\,\text{cm}=W=15\,\text{cm}$

_____

In general, solving for a particular variable involves "undoing" what has been done to the variable, usually in the reverse order. In part 4, the variable W has L added and the sum is multiplied by 2. We "undo" those operations, last operation first, by dividing by 2 and subtracting L.

The properties of equality say you can do what you like to an equation as long as you do the same thing to both sides of the equation. So, when we say "divide by 2", we mean "divide both sides of the equation by 2." Likewise, "subtract L" means "subtract L from both sides of the equation."

4 0

3 years ago

Sally found that out of 750 cans stamped in the ½ hour trial run, 150 were not stamped. About how many were not stamped in 3 hou

Vera_Pavlovna [14]

Answer:

<em>About 900 cans not stamped in 3 hours</em>

Step-by-step explanation:

<u>Proportions</u>

Sally found that 150 cans were not stamped in the 1/2 hour trial run.

Following the same proportion in time, we can say:

150 cans not stamped in 1/2 hour. Multiplying by 2:

300 cans not stamped in 1 hour. Multiplying by 3: