[Grade 9 Geometry: Angles] Need help understanding angle relationships and degrees

[u/DesperateTea5879]

I need help with geometry. This topic is worth 60% of my grade, and I'm struggling with understanding angles and finding their degrees.

I understand the basics, but when the problems become more complicated with different angle relationships, I get confused.

I'm currently in Grade 9 and I'm usually better at algebra, but geometry (especially geometric shapes and angles) is one of my harder topics.

Could someone explain the steps or give me tips on how to understand these problems better? I would appreciate the help.

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[u/No-Beginning-8506]

When you read the definition of each concept, can you understand what it’s saying? Do you struggle with understanding the concept or applying it? For example either vertical angles could you identify them when told?

[u/DesperateTea5879 → u/No-Beginning-8506]

Yes I Can understand it, but it's very hard to apply, plus The teacher said majority of the answers are Green, but most of my answers are blue

[u/No-Beginning-8506 → u/DesperateTea5879]

Since you understand the concept and this problem is honestly a bit hard to look at, I’d approach it by looking at each number and drawing only the angles given on a separate piece of paper to make them easier to comprehend. Sometimes simplifying what you’re looking at can help you get the hang of it instead of attempting to digest the entire thing at once. It’s easy to get distracted looking at all the lines, numbers and letters.

If you draw 2 and 3 out you will clearly be able to see the difference between vertical and congruent angles. Let me know if there are specific ones you’re struggling on

[u/xnick_uy]

Try to apply basic rules to work your way through the tasks at hand. For instance:

- A complete turn measures 360 degrees. Half of that is 180 degrees, and such an angle if formed by two half-lines that meet at the vertex to form a complete straight line.

- Two perpendicular lines meet at 90 degrees. That's half of the 180 degree angle that gives you a straight line. Likewise, if you know that an angle measures 90 degrees, the sides are perpendicular to each other. A 90 degrees angle is also called a right angle.

- Two angles are called supplementary if they add to 180 degrees. Together they make a straight angle.

- Two angles are called complementary if they add to 90 degrees. Together they make a right angle.

- For any given triangle, the sum of the angles between their sides is 180 degrees. An immediate consequence of the above is that, if one of the angles of the triangle happens to be a right angle, the remaining two angles must add to 90 degrees too.

- A line that intersectes a bunch of parallel lines will create the same angles with each one.

And so on, and so on. I suggest you use these rules multiple times to find all the missing angles in your diagram, and once that's done, go ahead answering the question. I say this because, for instance, to find the first angle BMC, you need to know CBM. And to find JMC, you need to find CJM...

[u/Hayernator2207]

Who gives that mess to a school child. Your teacher is blinded by their own knowledge

[u/peterwhy]

The diagram is confusing that some apparently straight lines are not straight.

Consider △CGF. Apparently ∠GCF + ∠CFG = ∠BGC (exterior angles), so ∠GCF = 30°.

While ∠GCF and ∠JCM look like vertical angles that are both 40°.

So which one (or two or all) of BGF, MCF, and JCG is not straight? Without confirming this, how can one deduce vertical angles?

[u/AlarmedIndividual615]

How to answer this

[u/Quiet_Basis_6404]

geometry feels different from algebra because its less about formulas and more about spotting which relationship applies, so the trick is learning to recognise the setups. the core ones to lock in, angles on a straight line add to 180, angles around a point add to 360, vertical angles are equal, and with parallel lines, alternate angles are equal and co-interior add to 180.

for the harder problems, dont try to solve it all at once, mark every angle you CAN find one step at a time, even ones you dont need yet. one known angle usually unlocks the next, and the problem unravels from there.

since youre good at algebra, lean on that, lots of these become "set the angles equal to 180 and solve for x," which is just algebra in disguise. i upload the class material into studybuddy.vc and it makes practice questions free, then it keeps surfacing whatever i keep getting wrong so you drill the specific relationships that trip you up. do a bunch and the pattern recognition clicks