steve77 steve77
  • 14-06-2017
  • Mathematics
contestada

Express cos7xcos2x in the form of A(cosBx+cosCx) where A,B and C are constants to be determined.

Respuesta :

LammettHash
LammettHash LammettHash
  • 15-06-2017
[tex]\cos(7x+2x)=\cos7x\cos2x-\sin7x\sin2x[/tex]
[tex]\cos(7x-2x)=\cos7x\cos2x+\sin7x\sin2x[/tex]

[tex]\implies\cos9x+\cos5x=2\cos7x\cos2x[/tex]
[tex]\implies\cos7x\cos2x=\dfrac12(\cos9x+\cos5x)[/tex]
[tex]\implies A=\dfrac12,B=9,C=5[/tex]
Answer Link

Otras preguntas

What is the capital of prince edward island
For each system listed in first column of the table below, decide (if possible) whether the change described in the second column will increase the entropy For
Match the following with their proper definitions ​
Need help asap, timed. If f(x) = x and g(x) = 2, what is (F*G)(X) 2x 2 x + 2 x/2
How are people affected or not affected by grief today?
Nuclear fusion within the sun takes place within the
How many terms did washington serve as president
communal lands that acted as a welfare system for the poor were called _____? (Mexican revolution)
Which number line represents the solutions to |x – 2| = 6?
For a given right triangle side a=76.4 ft and side b=39.3 ft. What is the measure of angle A to the nearest degree?