Formulae 公式

quadrilaterals 四边形

Refer to the last chapter for symbol representation.
Square and rhombus 正方形和菱形: 4s4s
Rectangle and parallelogram 长方形和平行四边形: 2(a+b)2(a+b) (aa and bb refer to the side length of two adjacent sides) (aabb 分别指两相邻边的长度)

ellipticals 椭圆形

Call a circle’s circumference (perimeter) CC and diameter dd. Then π=Cd\pi =\dfrac {C}{d} , so C=2πr=πdC=2\pi r=\pi d.
将一个圆的圆周和直径的长度分别称为 CCdd 。易得 C=2πr=πdC=2\pi r=\pi d

Techniques 技巧

When we meet irregular shapes, we can ‘move’ their perimeter without changing it’s value, as below.
当我们遇到不规则图形时,可以在不改边其周界长度当情况下边換其周界,如下。 Image 1.1.2-1 图1.1.2-1 Image 1.1.2-1 图1.1.2-1

Note by Jeff Giff
1 year ago

No vote yet
1 vote

  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.

MarkdownAppears as
*italics* or _italics_ italics
**bold** or __bold__ bold

- bulleted
- list

  • bulleted
  • list

1. numbered
2. list

  1. numbered
  2. 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]( 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"
MathAppears as
Remember to wrap math in \( ... \) or \[ ... \] to ensure proper formatting.
2 \times 3 2×3 2 \times 3
2^{34} 234 2^{34}
a_{i-1} ai1 a_{i-1}
\frac{2}{3} 23 \frac{2}{3}
\sqrt{2} 2 \sqrt{2}
\sum_{i=1}^3 i=13 \sum_{i=1}^3
\sin \theta sinθ \sin \theta
\boxed{123} 123 \boxed{123}


Sort by:

Top Newest

Jeff, this is good, but I don't understand Chinese.

Is there any other languages apart from Chinese and English that you can speak?

Yajat Shamji - 1 year ago

Log in to reply


Jeff Giff - 1 year ago

Log in to reply

Sorry :/

Jeff Giff - 1 year ago

Log in to reply

That's okay.

Yajat Shamji - 12 months ago

Log in to reply


Problem Loading...

Note Loading...

Set Loading...