Need math help with trig identities

Anonymous
timer Asked: Nov 5th, 2015
account_balance_wallet $5

Question Description

prove the identity:

1) sin4x = 2sin2xcos2x

2)cos6x = 2cos^2 3x-1

3)sin3x = sin x(4cos^2 x-1)

Tutor Answer

ipesuni
School: Cornell University

Thank you for the opportunity to help you with your question!

1)We can prove the identity using the formula ,sin(2A)=2sinAcosA

Here A=2x

therefore,

2)cos(6x)

We have the double angle formula for cos 2A

On comparing here A=3x

Thus,

3)sin(3x)

It can be written as

sin(x+2x)

Using the sum of angle formula for sin(A+B)=sinAcosB+cosBsinA


Substitute,

Factoring out sinx

                  =

                 =


---Thanks--------

;)


 





Please rate my answer so that I can help you further in the future.

flag Report DMCA
Review

Anonymous
awesome work thanks

Brown University





1271 Tutors

California Institute of Technology




2131 Tutors

Carnegie Mellon University




982 Tutors

Columbia University





1256 Tutors

Dartmouth University





2113 Tutors

Emory University





2279 Tutors

Harvard University





599 Tutors

Massachusetts Institute of Technology



2319 Tutors

New York University





1645 Tutors

Notre Dam University





1911 Tutors

Oklahoma University





2122 Tutors

Pennsylvania State University





932 Tutors

Princeton University





1211 Tutors

Stanford University





983 Tutors

University of California





1282 Tutors

Oxford University





123 Tutors

Yale University





2325 Tutors