A circular pool has a radius of 20 feet. What is the area of the pool? Use 3.14 for π.
2 answers:
The formula for area is
However, we are substituting pi for 3.14, so in this case the formula is 3.14×r^2
Here's a non-calculator method:
When r=20, A=3.14×20^2
20^2=400
Let's convert 3.14 into an integer by multiplying by 100, so we can deal with the numbers more easily:
314×400=(314×400)×100=125600
Now divide by 100 to put the decimal places of 3.14 back:
125600÷100=1256
If you noticed, we could have just cancelled out the decimal places in the 3.14 by dividing 400 by 100, meaning we could have just done 314×4
Besides this, the area of the pool is 1256ft^2
However, we are substituting pi for 3.14, so in this case the formula is 3.14×r^2
Here's a non-calculator method:
When r=20, A=3.14×20^2
20^2=400
Let's convert 3.14 into an integer by multiplying by 100, so we can deal with the numbers more easily:
314×400=(314×400)×100=125600
Now divide by 100 to put the decimal places of 3.14 back:
125600÷100=1256
If you noticed, we could have just cancelled out the decimal places in the 3.14 by dividing 400 by 100, meaning we could have just done 314×4
Besides this, the area of the pool is 1256ft^2
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Let's first rewrite it in vertex form.
Start by completing the square.
y = x² + 4x + 4 - 4 - 1
y = (x + 2)² - 5
(x + 2)² = y + 5
Now, 4a = 1; a =
So, the vertex form is (x + 2)² = 4()(y + 5)
So, we know that the vertex is at (-2, -5).
Since it's a concave up parabola, we just have to change the y-value to find the focus.
∴ F(-2, -5 +)
F(-2,
)
Start by completing the square.
y = x² + 4x + 4 - 4 - 1
y = (x + 2)² - 5
(x + 2)² = y + 5
Now, 4a = 1; a =
So, the vertex form is (x + 2)² = 4(
So, we know that the vertex is at (-2, -5).
Since it's a concave up parabola, we just have to change the y-value to find the focus.
∴ F(-2, -5 +
F(-2,