Well,i have on my side,the question and answer...
I just want the expalanation of this sum please....
Q: express as sum or difference of
1)2sin2A.cosA
2)2cos2A.cosA
Solution:
1)2sin2A.cosA= sin(2A+A)+sin(2A-A)=sin3A+sinA
2)2cos2A.cosA= cos(2A+A)+cos(2A-A)=cos3A+cosA
Also ,it will be of great help if someone will help with giving easy tips on solving with
multiple angle identities...
2006-09-17 01:20:04 · 2 answers · asked by lucky21 2 in Education & Reference ➔ Homework Help
The solution is from the text book. It cant be wrong..
2006-09-17 01:45:42 · update #1
the first terms in your answer are wrong.
2 sin2a is not equal to sin(2a+a)
Here is a possible solution.
You must know this.
sin2a=2sina cos a
2sin2acosa=2. 2sina cosa . cosa
=4 sina cos^2 a ( remember : sin^2a+cos^a=1)
=4sina (1-sin^2 a)
=4sina - 4sin^3 a
In the same way the answer for the second question will be
4cos^3 a - 2 cos a
2006-09-17 01:30:42 · answer #1 · answered by iyiogrenci 6 · 3⤊ 0⤋
Your answer is wrong i think....Please check it again that the answer is correct.
2006-09-17 08:39:46 · answer #2 · answered by Celine 2 · 0⤊ 1⤋