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## Comment on

Intersection and Arc## Do we need to memorize these

My Exam is less than 10 days and I have no time to memorize ALL of them :(

## You are not provided with any

You are not provided with any formulas when taking the GRE.

## My exam is in 12 days and I

## Here are a few articles that

Here are a few articles that might help.

Silly Mistakes

- https://www.greenlighttestprep.com/articles/avoiding-silly-misteaks-gre

Proper Mindset:

- http://www.greenlighttestprep.com/articles/mindset-and-body-language-gre...

- http://www.greenlighttestprep.com/articles/junior-girls-volleyball-scori...

## Great! For everything you a

## We have been asked to find

## The formula used in the

The formula used in the solution is the formula for finding arc length.

There is no such thing as the area of an arc. If you're thinking about the formula for finding the area of a sector, that formula is:

Area = (central angle/360)(pi)(radius²)

More here: https://www.greenlighttestprep.com/module/gre-geometry/video/879

## This question is from Kaplan

Qn.: Circle A and circle B have their centers at points A and B, respectively. If point A lies on circle B, point B lies on circle A, and line segment AB has a length of 6, what is the area of region that lies within both circle A and circle B?

A) 12π - 6√2

B) 12π - 12√3

C) 24π - 6√3

D) 24π - 18√3

E) 24π - 24√2

## Very interesting. That's

Very interesting. That's pretty much the same question as ours: https://www.greenlighttestprep.com/module/gre-geometry/video/1341

As you'll see, it's a long solution. I'm not sure if there's a faster way.

## I was able to find Y no

## If you had no problem getting

If you had no problem getting to the point where the length of arc length of CDE = (2/9)(60pi), then here's where we need to go from there:

arc length of CDE = (2/9)(60pi)

= (2/9)(60pi/1)

= (120pi)/9 [I multiplied numerators and denominators]

= (40pi)/3 [I divided top and bottom by 3]

= Answer choice D

## I didn't know the formula, so

80 / 360 = s / 60π Where s is the arc length

4800π = 360s

40π / 3 = s

Answer is D

## Perfect approach!!

Perfect approach!!

## Please if O is the center

## Hi Angel,

Hi Angel,

Which angle are you saying should equal x-90 degrees?

Cheers,

Brent

## Please I meant Angle X.

## You're correct to conclude

You're correct to conclude that, since O is the center, AO = OC. However, this does not mean that ∠AOC = 90°

If we add an imaginary line from A to C, we can see that ∆AOC is an ISOSCELES triangle, in which ∠OAC = ∠OCA, but we can't make any conclusions about the values of any of the angles inside ∆AOC.

To make conclusions about the angles inside ∆AOC, we need to use additional information.

Does that help?

Cheers,

Brent

## I didn't notice the line, I

x-y = 20, means x = y +20. Opposite angles are equal which means we have 2(y+20) + 2 (y) = 360 ==> 40 +4y = 360 ==> y = 80.

then use the length of arc formula and the given radius to get the required result.

## That's a perfectly-logical

That's a perfectly-logical approach. Nice work!!

## I did it like this:

So w + x + y + O = 360

w = y (opposite angles)

x = 20 + w --> x = 20 + y

O = x = 20 + y

So we have:

y + (20 + y) + y + (20 + y) = 360

4y + 40 = 360

4y = 320

y = 80

Then plug this into the formula!

## That works perfectly. Nice

That works perfectly. Nice work!!!