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#1 2013-04-19 01:07:59

demha
Full Member

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Supplementary and Complementary Angles

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

---

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

#2 2013-04-19 01:38:13

Agnishom
Real Member
Award: Wink Sherlock

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Re: Supplementary and Complementary Angles

Complementary Angles: Pair of angles whose sum is 90o.

Supplementary Angles: Pair of angles whose sum is 180o.

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'
'Who are you to judge everything?' -Alokananda

#3 2013-04-19 02:19:10

bob bundy
Moderator

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Re: Supplementary and Complementary Angles

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.

---

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


You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

#4 2013-04-26 00:22:58

demha
Full Member

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Re: Supplementary and Complementary Angles

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

#5 2013-04-26 02:14:41

bob bundy
Moderator

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Re: Supplementary and Complementary Angles

OK, good news!  Thanks for letting me know.  smile

Bob


You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

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