I'm confused with complementary angles and supplementary angles. How do you tell which angle is which?

Two angles are called complementary when their measures add to 90 degrees. Two angles are called supplementary when their measures add up to 180 degrees. One way to avoid mixing up these definitions is to note that s comes after c in the alphabet, and 180 is greater than 90.

why does math even exist

I don't know man. I don't know.

About question 1, I hope there is a clear explanation on why ∠DAP and ∠BPD do not add up to 90°. I guess there is some reason why ∠DAP and ∠BPD being supplementary or complementray is a contradiction, but i couldn't figure out what it is.

They might be complementary or supplementary, but you don't have enough information to prove that. There are no parallel lines, so you can't try and solve it using any of the parallel lies and a transversal rules. No vertical angles will end up helping you. I guess you can't really have a clear answer, unless you can prove that the angles cannot be complementary or supplementary.

I need help with practice step 2. Thank you.

What exactly are you confused about? If you can be more specific with what you need assistance for I will be glad to walk you through it :)

I don't quite understand Complementary and Supplementary angles.

Two angles are called complementary if their measures add to 90 degrees, and called supplementary if their measures add to 180 degrees. Note that in these definitions, it does not matter whether or not the angles are adjacent; only their measures matter. For example, a 50-degree angle and a 40-degree angle are complementary; a 60-degree angle and a 120-degree angle are supplementary.

What are vertical angles? I am asking this because I have some trouble identifying this certain type of angle.

say angle A is on one side of the vertex and angle B is on the opposite side, since they share a vertex and are on the opposite side of said vertex, they are vertical

Main content

Get ready for Geometry

Course: Get ready for Geometry > Unit 1

Lesson 4: Vertical, complementary, and supplementary angles

Complementary and supplementary angles review

CCSS.Math:

7.G.B.5

Google Classroom

Review the basics of complementary and supplementary angles, and try some practice problems.

Complementary angles

Complementary angles are two angles with a sum of 90, degrees. A common case is when they form a right angle.

[Show me]

Supplementary angles

Supplementary angles are two angles with a sum of 180, degrees. A common case is when they lie on the same side of a straight line.

[Show me]

Want to learn more about complementary and supplementary angles? Check out this video.

Practice set 1: Identify complementary and supplementary angles

Problem 1A

Current

What is the relationship between angle, A, X, Y and angle, Y, X, B?
All segments that appear straight are straight.

Want to try more problems like this? Check out this exercise.

Practice set 2: Find a missing angle measure

Problem 2A

Current

If angle, A, O, C is a right angle and m, angle, A, O, B, equals, 79, degrees, what is m, angle, B, O, C?
Note: Angles not necessarily drawn to scale.

degrees

Want to try more problems like this? Check out this exercise.

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Christian Imperio
Posted 4 years ago. Direct link to Christian Imperio's post “I'm confused with complem...”
I'm confused with complementary angles and supplementary angles. How do you tell which angle is which?
Button navigates to signup pageComment on Christian Imperio's post “I'm confused with complem...”
(33 votes)
Answer
- Ian Pulizzotto
  Posted 4 years ago. Direct link to Ian Pulizzotto's post “Two angles are called com...”
  Two angles are called complementary when their measures add to 90 degrees.
  Two angles are called supplementary when their measures add up to 180 degrees.
  
  One way to avoid mixing up these definitions is to note that s comes after c in the alphabet, and 180 is greater than 90.
  Comment on Ian Pulizzotto's post “Two angles are called com...”
  (72 votes)
Walter Montgomery
Posted 3 years ago. Direct link to Walter Montgomery's post “How do they come up with ...”
How do they come up with names for things in math?
Button navigates to signup pageComment on Walter Montgomery's post “How do they come up with ...”
(32 votes)
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- prehistoric-rishi
  Posted 4 months ago. Direct link to prehistoric-rishi's post “probably latin”
  probably latin
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  (6 votes)
aesd345635
Posted a month ago. Direct link to aesd345635's post “why does math even exist”
why does math even exist
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(21 votes)
Answer
- Sage Moon
  Posted a month ago. Direct link to Sage Moon's post “I don't know man. I don't...”
  I don't know man. I don't know.
  Comment on Sage Moon's post “I don't know man. I don't...”
  (11 votes)
Jae Hyun Kim
Posted 3 years ago. Direct link to Jae Hyun Kim's post “About question 1, I hope ...”
About question 1, I hope there is a clear explanation on why ∠DAP and ∠BPD do not add up to 90°. I guess there is some reason why ∠DAP and ∠BPD being supplementary or complementray is a contradiction, but i couldn't figure out what it is.
Button navigates to signup pageComment on Jae Hyun Kim's post “About question 1, I hope ...”
(15 votes)
Answer
- Hecretary Bird
  Posted 3 years ago. Direct link to Hecretary Bird's post “They might be complementa...”
  They might be complementary or supplementary, but you don't have enough information to prove that. There are no parallel lines, so you can't try and solve it using any of the parallel lies and a transversal rules. No vertical angles will end up helping you. I guess you can't really have a clear answer, unless you can prove that the angles cannot be complementary or supplementary.
  Comment on Hecretary Bird's post “They might be complementa...”
  (7 votes)
GoodTimeWithXion
Posted 10 months ago. Direct link to GoodTimeWithXion's post “One tip that helps me wit...”
One tip that helps me with remembering which name goes with which angles...

- "C" is in 'Corner' and 'Complementary'
- "S" is in 'Straight' and 'Supplementary'

A corner is always 90 degrees...
and a straight line is always 180 degrees!

So if it makes a corner, it's 'C' for 'Complementary'
if it makes a straight line, it's 'S' for 'Supplementary'
Button navigates to signup pageComment on GoodTimeWithXion's post “One tip that helps me wit...”
(17 votes)
Answer
.
Posted a month ago. Direct link to .'s post “O I'm a goofy goober yeah...”
O I'm a goofy goober yeah you're a goofy goober yeah we're all goofy goobers yeah goofy goofy goobers yeah
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(10 votes)
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- Sage Moon
  Posted a month ago. Direct link to Sage Moon's post “Rock”
  Rock
  Comment on Sage Moon's post “Rock”
  (3 votes)
Veerrohit
Posted 6 years ago. Direct link to Veerrohit's post “What are vertical angles?...”
What are vertical angles? I am asking this because I have some trouble identifying this certain type of angle.
Button navigates to signup pageComment on Veerrohit's post “What are vertical angles?...”
(0 votes)
Answer
- leonh
  Posted 2 years ago. Direct link to leonh's post “say angle A is on one sid...”
  say angle A is on one side of the vertex and angle B is on the opposite side, since they share a vertex and are on the opposite side of said vertex, they are vertical
  Comment on leonh's post “say angle A is on one sid...”
  (8 votes)
lmudge
Posted 3 years ago. Direct link to lmudge's post “I need help with practice...”
I need help with practice step 2. Thank you.
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(4 votes)
Answer
- Dayla
  Posted 3 years ago. Direct link to Dayla's post “What exactly are you conf...”
  What exactly are you confused about? If you can be more specific with what you need assistance for I will be glad to walk you through it :)
  Button navigates to signup page
  (11 votes)
Silvia
Posted 3 years ago. Direct link to Silvia's post “I don't quite understand ...”
I don't quite understand Complementary and Supplementary angles.
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(2 votes)
Answer
- Ian Pulizzotto
  Posted 3 years ago. Direct link to Ian Pulizzotto's post “Two angles are called com...”
  Two angles are called complementary if their measures add to 90 degrees, and called supplementary if their measures add to 180 degrees. Note that in these definitions, it does not matter whether or not the angles are adjacent; only their measures matter.
  
  For example, a 50-degree angle and a 40-degree angle are complementary; a 60-degree angle and a 120-degree angle are supplementary.
  Button navigates to signup page
  (14 votes)
SonicTheHedgehog
Posted a month ago. Direct link to SonicTheHedgehog's post “Like this comment now! ...”
Like this comment now!
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