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Mathematics 10 Online
OpenStudy (anonymous):

A polygon has n sides. Two of its angles are right angles. Each of the remaining angles equal to 150 degrees. calculate n. Please help! =)

Parth (parthkohli):

Do you know the sum of angles in ANY \(n\)-sided polygon?

OpenStudy (anonymous):

n-2X180 degrees

Parth (parthkohli):

That's right. Two angles make up 180 degrees, and what is the sum of the rest of your angles?

Parth (parthkohli):

You are left with this mess:\[180(n -2) = 150(n - 2) + 180\]

OpenStudy (anonymous):

Im not really understanding :\

Parth (parthkohli):

OK, let's see how I can make you understand.

Parth (parthkohli):

The sum of angles in ANY polygon is \(180(n -2)\) right?

OpenStudy (anonymous):

Right

Parth (parthkohli):

Two angles of this particular polygon are right angles. Do you know what a right angle is?

OpenStudy (anonymous):

Yes

Parth (parthkohli):

So what'd be the sum of these two right angles?

OpenStudy (anonymous):

A right angle measures 90 degrees

OpenStudy (anonymous):

180 degrees

Parth (parthkohli):

Nice, now what'd the sum of the rest of the angles be?

OpenStudy (anonymous):

150 degrees

Parth (parthkohli):

But what'd the \(\textbf{sum}\) of them be?

OpenStudy (anonymous):

I dont know :\ the sum is unknown :\

Parth (parthkohli):

In terms of \(n\), what'd it be?

OpenStudy (anonymous):

150 (N-2)

Parth (parthkohli):

Yeah, so the sum of angles is \(150(n - 2) + 180\), but it also is \(180(n - 2)\). So those two are equal.

Parth (parthkohli):

Now solve for \(n\)! :-)

OpenStudy (anonymous):

Im still not getting it :(

OpenStudy (anonymous):

Thanks for your help anyways :-)

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