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**demha****Member**- Registered: 2012-11-25
- Posts: 195

This is my Geometry lesson. I could use some help checking to see if I got them right or wrong. There are two here I do not know how to solve which I could use help with.

1. 87 - I said C

A 77

B24

C93

D47

E 31

F 48

2. 160 - I said A

A 10

B20

C30

D40

E 50

F 60

3. 68 - I said E

A 851

B295

C302

D574

E 112

F 638

4. 174 - I said D

A 3

B4

C5

D 6

E 7

F 8

5. a - Not sure how to solve, need help

A 180-a

B180/2

C 179*a

D 179+a

E 60

F pi

Find the complementary angles of the following.

6. 53 - I said F

A 90

B32

C 25

D 45

E 18

F 37

7. 12 - I said B

A 46

B78

C98

D31

E 52

F 64

8. 73.5 - I said A

A 16.5

B34.2

C29.4

D17.7

E 57.9

F 11.3

9. 23.7 - I said A

A 66.3

B70.1

C42.5

D83.9

E 54.8

F 36.2

10. a - Also not sure how to solve this one

A 90/a

Ba-90

Ca/2

D90-a

E 90-2

F a^2

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I could also use some help understanding how to solve this. I believe I have to find the the third angle for the triangle:

a, (a + 80)

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

~Abraham Lincoln

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**Complementary Angles: ** Pair of angles whose sum is 90[sup]o[/sup].

**Supplementary Angles: ** Pair of angles whose sum is 180[sup]o[/sup].

Example - Find the complementary angle of 53

Let the required angle be x

Therefore, x + 53 = 90

==> x = 90 - 53 = 37

Thus, the required complementary angle of 53 is 37

Example - Find the supplementary angle of 53

Let the required angle be x

Therefore, x + 53 = 180

==> x = 180 - 53 = 127

Thus, the required supplementary angle of 53 is 127

The complimentary angle of a is 90 - a

The supplementary angle of a is 180 - a

'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

I'm not crazy, my mother had me tested.

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**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 7,613

hi demha

I assume these are supplementary angles.

1. 87 - I said C

A 77

B24

C93

D47

E 31

F 48

correct

2. 160 - I said A

A 10

B20

C30

D40

E 50

F 60

160 + 10 is not 180

3. 68 - I said E

A 851

B295

C302

D574

E 112

F 638

correct

4. 174 - I said D

A 3

B4

C5

D 6

E 7

F 8

correct

5. a - Not sure how to solve, need help

A 180-a

B180/2

C 179*a

D 179+a

E 60

F pi

a plus something makes 180. Which of these answers fits the something?

Find the complementary angles of the following.

6. 53 - I said F

A 90

B32

C 25

D 45

E 18

F 37

correct

7. 12 - I said B

A 46

B78

C98

D31

E 52

F 64

correct

8. 73.5 - I said A

A 16.5

B34.2

C29.4

D17.7

E 57.9

F 11.3

correct

9. 23.7 - I said A

A 66.3

B70.1

C42.5

D83.9

E 54.8

F 36.2

correct

10. a - Also not sure how to solve this one

A 90/a

Ba-90

Ca/2

D90-a

E 90-2

F a^2

Similar to Q5. This time you want a plus something makes 90.

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I could also use some help understanding how to solve this. I believe I have to find the the third angle for the triangle:

a, (a + 80)

Angles must add to 180.

So angle 1 plus angle 2 plus angle 3 = 180 => angle 3 = 180 -(angle 1 plus angle 2)

angle 3 = 180 - (a + a + 80)

Can you simplify the algebra from here?

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

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**demha****Member**- Registered: 2012-11-25
- Posts: 195

Hi Bob,

I sent in my lesson and got all of them but #2 right. I sent in #2 and said the answer was B, 20. I got a 10 on my lesson!

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

~Abraham Lincoln

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**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 7,613

OK, good news! Thanks for letting me know.

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

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