a) prove that sin^2mx-sin^2nx = sin(m+n)x sin(m-n)x
b) hence, solve
sin^2 9x-sin^2 5x + sin4x = 0
for 0<90
Compound Angles
2008-02-03 10:11 pm
回答 (1)
2008-02-03 10:34 pm
收錄日期: 2021-04-25 17:17:57
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20080203000051KK01427