a. maths
2007-03-27 2:20 am
Using the formula tan2A=(2tanA)/[1-(tanA)^2],express tan22.5 in surd form
回答 (1)
2007-03-27 2:28 am
✔ 最佳答案
tan45=(2tan22.5)/[1-(tan22.5)^2]1=(2tan22.5)/[1-(tan22.5)^2]
[1-(tan22.5)^2]=2tan22.5
(tan22.5)^2+2tan22.5-1=0
tan22.5= [-2+/-(4+4)^(1/2)]/2
= -1+/-[2^(1/2)]
As tan22.5is possitive
=-1+[2^(1/2)]
收錄日期: 2021-05-01 09:38:40
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20070326000051KK02957