Question

Write the expression as either the sine, cosine, or tangent of a single angle.

cos(pi/3)cos(pi/5) + sin(pi/3)sin(pi/5)

Answer 1

use the compound identity cos (a - b) = cosacosb +sinasinb

Answer 2

now insert a = pi/3 and b = pi/5 and work out lefthand side and you've got it

Answer 3

do you gollow me?

Answer 4

kind of, not entirely

Answer 5

lol * follow i meant!

Answer 6

haha i got what you meant

Answer 7

you just need to simplify cos (pi3 - pi/5)

Answer 8

you need to get a common denominator right?