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4 years ago

Identify the radius and the center of a circle whose equation is (x – 5)² + y² = 81.

Mathematics

2 answers:

koban [17]4 years ago

6 0

Answer:

9, (5,0)

Step-by-step explanation:

Facts

ipn [44]4 years ago

5 0

Answer:

Center = (5, 0)

Radius = 9

Step-by-step explanation:

Look at the picture

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Helps me! find the area please. ＼（〇_ｏ）／

Anon25 [30]

We must remember the equation to find the area of a trapezoid first.
Area = $\frac{A+B}{2} *H$
A and B are the bases (6 and 12)
The height is 6 for each trapezoid
Now Solve!
====================================================================
SOLVING...

Area = $\frac{6 + 12}{2} * 6$
Area = $\frac{18}{2} * 6$
Area = 9 * 6
Area = 54

Since there are two trapezoids, multiply 54 by 2
54 x 2 = 108
Area = 108

7 0

3 years ago

I don’t understand this.. <br> will someone please help? Will mark Brainliest along with 20 points.

inn [45]

To say two quantities $a$ and $b$ "vary directly" with one another means that a change in one of the quantities results in a proportional change in the other quantity. For example, if $a=2b$ , then $b$ is proportional to $a$ by a factor of 2, or $a$ is proportional to $b$ by a factor of 1/2. In other words, if you change $b$ by some fixed amount, then $a$ changes by double that amount.

Mathematically this means there is some constant scaling factor $k$ such that $a=kb$ . In question 4, we're told $f(x)$ varies directly with $x^2$ , which means there's some $k$ such that

$f(x)=kx^2$

We're given that $f(x)=40$ when $x=2$ , so

$40=k\cdot2^2\implies40=4k\implies k=10$

Then when $x=5$ , we get

$f(5)=10\cdot5^2=10\cdot25=250$

- - -

For $a,b$ to "vary inversely" with one another means that a change in one quantity results in an "opposite" change in the other. In other words, if $a$ increases, then $b$ decreases, and vice versa.

Mathematically, this is the same as saying there is some fixed number $k$ such that $ab=k$ .

For example, if $k=1$ and we start with $a=1$ , then $b=1$ also. If we change to $a=2$ , then $b=\dfrac12$ ; if $a=10$ , then $b=\dfrac1{10}$ , and so on.