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**Lauren1415****Member**- Registered: 2018-10-17
- Posts: 5

Supplementary and Complementary Angles

I need help with these problems, please.

18. a, (a + 80)

A100 - 2a

B112 - 7a

C182 - 2a

D254 - 5a

E 311 - 3a

F 302 - 1a

Im guessing either a or b because they are under 180 degrees.

19. x, (x + 20)

A189 - 7x

B167 - 1x

C114 - 5x

D160 - 2x

E 124 - 2x

F 142 - 1x

20. m, 2m

A172 - 2m

B187 - 7m

C124 - 4m

D143 - 1m

E 164 - 9m

F 180 - 3m

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**Strangerrr****Member**- Registered: 2018-07-28
- Posts: 23

18. a, (a + 80)

A100 - 2a

B112 - 7a

C182 - 2a

D254 - 5a

E 311 - 3a

F 302 - 1a

what will give 180, if you plug it in the problem?

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**Strangerrr****Member**- Registered: 2018-07-28
- Posts: 23

Same thing for 19, what will give you 180.

19. x, (x + 20)

A189 - 7x

B167 - 1x

C114 - 5x

D160 - 2x

E 124 - 2x

F 142 - 1x

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**Strangerrr****Member**- Registered: 2018-07-28
- Posts: 23

And 20.

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**bob bundy****Administrator**- Registered: 2010-06-20
- Posts: 8,442

hi Lauren1415

Welcome to the forum.

I'm guessing that you were happy with your answers to 1 - 17. Somewhere around about Q15 or Q16 it explained what the problem means. You forgot to tell us that bit

Looking at the possible answers and also Strangerrr's answers I'm further guessing you were told that two out of three angles are given and are supplementary, and you have to work out the third angle.

So, for Q18, add the two together a + a + 80 = 2a + 80, and then subtract from 180, 180 - (2a + 80) and I'll leave you to simplify.

Were the earlier ones numbers with no algebra? Here's a way to make Q18 similar. Make up a value for 'a' , eg a = 30. Then the given angles become 30 and 110 and so the third angle is 180 - (30 + 110) = 40. Substitute a = 30 into each of the possible answers. Only one will give 40. That's the one.

Hope that helps,

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 Bundy

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**Lauren1415****Member**- Registered: 2018-10-17
- Posts: 5

Thank you! I think I was just overthinking these problems, haha.

Yes,sorry, this problems means, "Two of the angles are listed. Find the measure of the third angle in each triangle."

Yes, they earlier questions didn't have algebra, I understood those.

18. a, (a + 80)

A100 - 2a

B112 - 7a

C182 - 2a

D254 - 5a

E 311 - 3a

F 302 - 1a

A is my answer.

19. x, (x + 20)

A189 - 7x

B167 - 1x

C114 - 5x

D160 - 2x

E 124 - 2x

F 142 - 1x

D is my answer.

20. m, 2m

A172 - 2m

B187 - 7m

C124 - 4m

D143 - 1m

E 164 - 9m

F 180 - 3m

My answer is B.

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**bob bundy****Administrator**- Registered: 2010-06-20
- Posts: 8,442

hi Lauren1415

I think Q18 and Q19 are correct, but not Q20. Add up m and 2m and subtract from 180.

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 Bundy

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**Lauren1415****Member**- Registered: 2018-10-17
- Posts: 5

Thank you!

I received a perfect score on my lesson!

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**bob bundy****Administrator**- Registered: 2010-06-20
- Posts: 8,442

hi Lauren1415

Thanks for posting back with that result. Well done! It was a pleasure to help you.

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 Bundy

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