Forgot password
 Register account
View 2177|Reply 4

[几何] 征解

[Copy link]

2

Threads

4

Posts

0

Reputation

Show all posts

张振华 posted 2014-4-18 20:25 |Read mode
已知A,B,C,D四点在半径为(14^0.5)/2的球面上,且AC=BD=5^0.5,AD=BC=10^0.5,AB=CD,则三棱锥D-ABC的体积是______

84

Threads

2340

Posts

4

Reputation

Show all posts

其妙 posted 2014-4-18 20:49
对不对?已知$A,B,C,D$四点在半径为$\dfrac{\sqrt{14}}2$的球面上,且$AC=BD=\sqrt5,AD=BC=\sqrt{10},AB=CD,$则三棱锥$D-ABC$的体积是______

673

Threads

110K

Posts

218

Reputation

Show all posts

kuing posted 2014-4-18 20:51
看样子是构造长方体……

84

Threads

2340

Posts

4

Reputation

Show all posts

其妙 posted 2014-4-18 21:28
回复 3# kuing
,对棱都相等的四面体叫等腰四面体,其体积有公式的。外接球半径也是有公式的.甚至内切球半径也是有公式的.

2

Threads

4

Posts

0

Reputation

Show all posts

original poster 张振华 posted 2014-4-18 21:40
回复 2# 其妙
对的

Quick Reply

Advanced Mode
B Color Image Link Quote Code Smilies
You have to log in before you can reply Login | Register account

$\LaTeX$ formula tutorial

Mobile version

2025-7-21 11:56 GMT+8

Powered by Discuz!

Processed in 0.012776 seconds, 22 queries