Write the expression as the sine, cosine, or tangent of an angle. cos 8x cos 2x - sin 8x sin 2x

 cos (A - B) =  cos 6 x

Step-by-step explanation:

given equation,

     = cos 8 x . cos 2 x - sin 8 x . sin 2 x

   using identity

cos (A - B)  = cos (A) . cos(B) -  sin (A) . sin(B)(1)

cos 8 x . cos 2 x - sin 8 x . sin 2 x(2)

comparing both the equation (1) and (2)

we get ,

A = 8 x         B = 2 x

hence, from the above identity we can see that

cos (A - B)  = cos (8 x - 2 x)

 cos (A - B) =  cos 6 x

i would say c is the best answer, hope it's right!

good luck! =)

cutie~

arithmetic sequence

step-by-step explanation:

given that a sequence has terms as

19, 15, 11,

this is represented on a graph

the pattern indicates that the sequence is an arithmetic sequence with i term

a=19 and common difference d =-4

any general term

thus the sequence is reduced by 4 for each successive term starting from 1 and nth term is

24-5n.

first negative term would start after 5th term

5th term =24-25< 0

from 5th term onwards the sequence would be negative.