2sina=cosb 2sinb=5cosa 2sinr=5cosa. 則cosa的平方加cosb平方加cosr平方等於多少?
回答 (1)
2015-10-05 1:42 am
2SinA=CosB，2SinB=5CosA，Sinr=5CosA則Cos^2 +Cos^2 B+Cos^2 R等於多少?
Sol
2SinA=CosB
20SinA=10CosB…….
2SinB=5CosA
10SinB=25CosA…….
100=100Cos^2 B+100Sin^2 B
=400Sin^2 A+625Cos^2 A>400(不合)
無解
Sol
2SinA=CosB
20SinA=10CosB…….
2SinB=5CosA
10SinB=25CosA…….
100=100Cos^2 B+100Sin^2 B
=400Sin^2 A+625Cos^2 A>400(不合)
無解
收錄日期: 2021-04-30 20:11:44
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20151004061922AAmXR8Z