Question

2. What is the circumference of the circle?

e) 26π cm²
g) 6767 cm²
f) 52π cm²
h) 1697 cm²

Answer 1

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`Hello`
`There!`

We are looking for the circumference of the circle.

It's not hard, I promise! I will take you through a few steps, and we'll find the answer.

Are you ready? Then let's begin...:)

`Procedure:`

First, we need a formula for the circumference. We can't find the circumference without a formula!

· Luckily, there is a formula for the circumference:

⇒
`C=\pi d}`

Whoa. What's that?!

No worries, I'll clarify everything in a moment. :)

We are looking for the circumference.

In this formula, what stands for the circumference?

That's right,
`C`.

Now, what is this:
`\pi`?

This letter stands for pi - a constant in maths that comes in handy when we're searching for the circumference of a circle (or area).

It has an infinite number of digits after the decimal point, and these digits never repeat!

You might be thinking, "Oh no! Are we really going to use that infinite number?!"

The answer is "No". Mostly, we use 3.14 for
`\pi`, because these are the first three digits of pi, but since we aren't asked to use 3.14 for pi, we just press the
`\boxed{\pi }` button on our calculator.

Whew!

And then last but not least, we see "d". This isn't a constant, this is the diameter.

Checking our provided information, we see that the diameter is 26 cm.

Now, we substitute 26 for d:

`\bold{C=\pi (26)}`

`\bold{C=\pi *26}`

And now all we have to do is type these numbers into our calculator, and find the answer:

`\bold{C\approx81.7\:cm}`

Hooray! We've found the circumference!

But wait - why isn't 81.7 an option?

Because what we need to do is write it in terms of pi, which is even easier, because we just substitute 26 for d:

`\bold{C=\pi *26}`

➢ Rearrange the order of the terms:

`\bold{C=26\pi \:cm}`

▲ Circumference

Now there's another thing - why are all four options with units squared?

Circumference isn't measured in units squared, the area is!

▶︎ Incase you need the area, here it is:

`\bold{A=\pi r^(2)}`

A=Area (what we're looking for)

`\pi` = pi

Here we have a new variable - it's r, which is the radius.

Do you see that
`^2` next to r? It means that r is squared, or multiplied by itself.

You might be thinking, "But we don't have the radius!"

If we have the diameter, finding the radius is a piece of cake, because we divide the diameter by 2:

`\bold{26/2}`

`\bold{13}`

Now we substitute 13 for r and evaluate:

⇒
`\bold{A=\pi (13)^(2)}`

13 times itself is 169:

⇒
`\bold{A=169\pi \:cm^(2)}`

Whew! We're finally done!

• hope it's helpful!
• wishing you a great day!

`Greetings!`

--

Answer 2

26π cm

Explanation:

the circumference (C) of a circle is calculated as

C = πd ( d is the diameter )

= π × 26

= 26π cm