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demha

Member

Registered: 2012-11-25

Posts: 195

Geometry Review

So I just need help to make sure I got my answers right and there are also a few I was not too sure on how to do them, so help with those would be great

SO numbers 1 - 4 are referring to the image. It's only numbers 1 - 3 I'm not understanding too well on how to answer them. I would appreciate help with the first one (like a walk through) to help me understand. thanks!
REVIEW:

1.
Q. Refer to the image at the right. If angle 1 is 30 degrees, and angle 5 is 70 degrees, are the two lines parallel? Explain.

A.

2.
Q. Refer to the image at right. If angle 2 is 30 degrees and angle 4 is 60 degrees, are the lines parallel? Explain.

A.

3.
Q. Refer to the image at right. If angle 2 and angle 6 are both 70 degrees, are the lines parallel? Explain.

A.

4.
Q. Refer to the image at right. If the lines are parallel, and angle 4 is 50 degrees, what is the measure of angle 6?

A. Angle 6 will be 130 degrees.

5.
Q. What is the measure of the inner angle of a regular hexagon? Show your work (and be sure to explain anything you deem necessary to make sure your work is clear.)

A. A hexagon has 6 sides.
180 x 6 = 1080
The sum of the angles of deviation is 360
SO
1080 – 360 = 720
The final answer is 720

6.
Q. What is the measure of the inner angle of a regular decagon? Show your work (and be sure to explain anything you deem necessary to make sure your work is clear.)

A. A decagon has 10 sides.
180 x 10 = 1800
The sum of the angles of deviation is 360
SO
1800 – 360 = 1440

7.
Q. Polygon A has sides of 4, 3, 5, and 3. Polygon B has sides of 8, 6, 10, and 6. What are the two possible scale factors here? Explain.

A.
To get my scale factor, I will need to divide the two polygons. This is how I will do it along with the answers for each number:
4 / 8 = 1/2
3 / 6 = 1/2
5 / 10 = 1/2
3 / 6 = 1/2

So now we know the scale factor is 1:2.

8.
Q. A triangle has angles of 34 degrees, 56 degrees, and 90 degrees. It also have sides of 6, 8, and 10. Which side is across from which angle?

A.
Side 6 will be across angle 34.
Side 8 will be across angle 56.
Side 10 will be across angle 90.

9.
Q. A triangle has one angle measuring 52 degrees, and one angle measuring 18 degrees. What is the measure of the third angle?

A. The third angle’s measurement is 110 degrees.

10.
Q. A right triangle has a 90 degree angle, and an angle x. What will the measure of the third angle be?

A. I believe the answer for this would be 90 – x.

Last edited by demha (2013-06-24 03:43:28)

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"The thing about quotes on the Internet is you cannot confirm their validity"
~Abraham Lincoln

ShivamS

Member

Registered: 2011-02-07

Posts: 3,648

Re: Geometry Review

1. No, as 1 should = 5 if they are parallel and had a transversel through them. 

2. Also no, as co-interior angles are supplementary and thus 6+4 should = 180. 30 and 60 obviously are complementary, not supplementary.

3. Yes.

4. They are co-interior and thus supplementary. therefore, 50+x=180 and x=130. This, angle 6 is 130 degrees.

5. A bit of confusion. Do you mean to ask how much is each interior angle? If yes, the sum of interior angles in a regular polygon are the # of triangles 8 180 or (n-2)*180. 4*180 = 720 degrees. That is the sum of interior angles. each one is 720/n = 120 degrees.

6. Same concept as 5. 8*180 = 1440. Divide that by 10 and it is 144.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,626

Re: Geometry Review

hi demha

Have a look back to

http://www.mathisfunforum.com/viewtopic.php?id=19401

post 6.

When you have parallel lines the four acute angles are all the same and similarly the four obtuse ones are the same.

That should help with Q 1 2 and 3.

7.
Q. Polygon A has sides of 4, 3, 5, and 3. Polygon B has sides of 8, 6, 10, and 6. What are the two possible scale factors here? Explain.

A.
To get my scale factor, I will need to divide the two polygons. This is how I will do it along with the answers for each number:
4 / 8 = 1/2
3 / 6 = 1/2
5 / 10 = 1/2
3 / 6 = 1/2

So now we know the scale factor is 1:2.

That's good but the question says two possible scale factors.  You've given the small to large so the other will be ???

8.
Q. A triangle has angles of 34 degrees, 56 degrees, and 90 degrees. It also have sides of 6, 8, and 10. Which side is across from which angle?

A.
Side 6 will be across angle 34.
Side 8 will be across angle 56.
Side 10 will be across angle 90.

Correct

9.
Q. A triangle has one angle measuring 52 degrees, and one angle measuring 18 degrees. What is the measure of the third angle?

A. The third angle’s measurement is 110 degrees.

Correct

10.
Q. A right triangle has a 90 degree angle, and an angle x. What will the measure of the third angle be?

A. I believe the answer for this would be 90 – x.

Correct

Bob

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

ShivamS

Member

Registered: 2011-02-07

Posts: 3,648

Re: Geometry Review

Is this the compuhigh stuff again?

Bob

Administrator

Registered: 2010-06-20

Posts: 10,626

Re: Geometry Review

Is this the compuhigh stuff again?

Looks like it.

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

demha

Member

Registered: 2012-11-25

Posts: 195

Re: Geometry Review

7.
Would it be 2:1?

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"The thing about quotes on the Internet is you cannot confirm their validity"
~Abraham Lincoln

anonimnystefy

Real Member

From: Harlan's World

Registered: 2011-05-23

Posts: 16,049

Re: Geometry Review

Yup!

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“Here lies the reader who will never open this book. He is forever dead.
“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

demha

Member

Registered: 2012-11-25

Posts: 195

Re: Geometry Review

Thanks guys!

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"The thing about quotes on the Internet is you cannot confirm their validity"
~Abraham Lincoln

cooperblu

Member

Registered: 2020-11-05

Posts: 3

Re: Geometry Review

I'm having trouble with 1-3 and 9/10 from this homework. It's a different  but similar question now:

1. Refer to the image at the right. If angle 1 is 30 degrees, and angle 5 is 70 degrees, are the two lines parallel? Explain using the term for the relationship between these two angles.

2. Refer to the image at the right. If angle 4 is 70 degrees and angle 6 is 70 degrees, are the lines parallel? Explain using the term for the relationship between these two angles.

3. Refer to the image at the right. If angle 2 and angle 6 are both 70 degrees, are the lines parallel? Explain using the term for the relationship between these two angles.

9. A triangle has one angle measuring 52 degrees, and one angle measuring 18 degrees. What is the measure of the third angle?

10. A right triangle has a 90-degree angle and an angle x. What will the measure of the third angle be?

it still uses the same image though but I'm still confused :,<

Bob

Administrator

Registered: 2010-06-20

Posts: 10,626

Re: Geometry Review

hi cooperblu

I'm assuming the diagram is the one in the first post.

If AB is parallel to CD then the following angles are equal

1,5, 4 and 8.

and separately

2, 6, 3 and 7.

The words to use are;

1 and 5 are corresponding; 1 and 4 are vertically opposite; 3 and 6 are alternate.

These properties work both ways round so eg.  if angle 1 = angle 5 then the lines are parallel.

And if the lines are not parallel, then those angles are not equal [and if the angles are not equal then lines are not parallel].

Hope that helps,

Bob

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

cooperblu

Member

Registered: 2020-11-05

Posts: 3

Re: Geometry Review

Hi, I'm still getting 1-3 incorrect, these have been my most recent answer:

1. Refer to the image at the right. If angle 1 is 30 degrees, and angle 5 is 70 degrees, are the two lines parallel? Explain using the term for the relationship between these two angles.
No, they are not parallel, 1 and 5 are corresponding angles.

2. Refer to the image at the right. If angle 4 is 70 degrees and angle 6 is 70 degrees, are the lines parallel? Explain using the term for the relationship between these two angles.
No, they are not parallel, 4 and 6 are same-side interior.

3. Refer to the image at the right. If angle 2 and angle 6 are both 70 degrees, are the lines parallel? Explain using the term for the relationship between these two angles.
No, they are not parallel, 2 and 6 are corresponding angles.

Any tips on how to correct this?

Last edited by cooperblu (2021-02-07 06:42:38)

Bob

Administrator

Registered: 2010-06-20

Posts: 10,626

Re: Geometry Review

hi cooperblu,

You are right to say corresponding for Q1 and Q3,  In 1, they are not equal so the lines are not parallel.  In 3, the are equal so the lines are parallel.

In Q2, if angle 4 and angle 8 were equal then the lines would be parallel. Angle 6 and angle 8 must add up to 180.  If angle 6 is 70, that makes angle 8 =110 so the lines are not parallel.

Check: (i) Is the diagram correct?  (2) Have you been told be your tutor that your answers to Q1 and Q2 are not correct.

This page is worth a visit https://www.mathsisfun.com/geometry/cor … ngles.html

Bob

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob