Geometry and trigonometry (maybe?)

Can anybody recommend any sources to learn geometry? About level 3-4, I'm struggling in that on Brilliant as well as maths competitioms, when I often reach a dead end. Thanks for help.

Easy Math Editor

This discussion board is a place to discuss our Daily Challenges and the math and science related to those challenges. Explanations are more than just a solution — they should explain the steps and thinking strategies that you used to obtain the solution. Comments should further the discussion of math and science.

When posting on Brilliant:

Use the emojis to react to an explanation, whether you're congratulating a job well done , or just really confused .
Ask specific questions about the challenge or the steps in somebody's explanation. Well-posed questions can add a lot to the discussion, but posting "I don't understand!" doesn't help anyone.
Try to contribute something new to the discussion, whether it is an extension, generalization or other idea related to the challenge.
Stay on topic — we're all here to learn more about math and science, not to hear about your favorite get-rich-quick scheme or current world events.

Markdown	Appears as
`italics` or `_italics_`	italics
`bold` or `__bold__`	bold
- bulleted - list	bulleted list
1. numbered 2. list	numbered list
Note: you must add a full line of space before and after lists for them to show up correctly
paragraph 1 paragraph 2	paragraph 1 paragraph 2
`[example link](https://brilliant.org)`	example link
`> This is a quote`	This is a quote
# I indented these lines # 4 spaces, and now they show # up as a code block. print "hello world"	# I indented these lines # 4 spaces, and now they show # up as a code block. print "hello world"

Math	Appears as
Remember to wrap math in `$` ... `$` or `\[` ... `\]` to ensure proper formatting.
`2 \times 3`	$2 \times 3$
`2^{34}`	$2^{34}$
`a_{i-1}`	$a_{i-1}$
`\frac{2}{3}`	$\frac{2}{3}$
`\sqrt{2}`	$\sqrt{2}$
`\sum_{i=1}^3`	$\sum_{i=1}^3$
`\sin \theta`	$\sin \theta$
`\boxed{123}`	$\boxed{123}$

Comments

Sal's videos on Geometry and Trigonometry. A great site for learning all sorts of things! Not just geometry and trig. :-=P

Vishnuram Leonardodavinci - 7 years, 2 months ago

Hi, Vishnuram! You almost answer all of my problems that I made. Would you be so kind as to make the solutions of these problems that you've answered recently: Rolling Ball and Insane Integral? I would be really grateful for your kindness. :)

Tunk-Fey Ariawan - 7 years, 2 months ago

Geometry is not my department but you can have a look at Coxeter, Geometry revisited.

حكيم الفيلسوف الضائع - 7 years, 1 month ago

Challenges and thrills is a gud book for geometry according to me.

Prasad Nikam - 7 years, 2 months ago

Actually, most geometry questions make use of congruency and similarity so that is the place you should start with if you want to improve in geometry. Try different methods if you reach a dead end. :)

Jianzhi Wang - 7 years, 2 months ago

And don't forget another important method:transformation

King Zhang Zizhong - 7 years, 2 months ago

Thanks

Jianzhi Wang - 7 years, 1 month ago

Math	Appears as
Remember to wrap math in `\(` ... `\)` or `\[` ... `\]` to ensure proper formatting.
`2 \times 3`	$2 \times 3$
`2^{34}`	$2^{34}$
`a_{i-1}`	$a_{i-1}$
`\frac{2}{3}`	$\frac{2}{3}$
`\sqrt{2}`	$\sqrt{2}$
`\sum_{i=1}^3`	$\sum_{i=1}^3$
`\sin \theta`	$\sin \theta$
`\boxed{123}`	$\boxed{123}$