Question

cos65°cos5°+sin65°sin5°

Answer 1

How would I solve this using the
sum/diff formula
double angle formula
or 1/2 angle formula

Answer 2

cos(a-b)=cosacosb+sinasinb
cos(65°)cos(5°) + sin(65°)sin(5°)
=cos((65-5)°)
=cos(60°)
=1/2

Answer 3

1=cos(0)=cos(65-65)=cos65°cos5°+sin65°sin5°

Answer 4

If I remember correctly that cos(0) equals 1.

Answer 5

hold up im absorbing this

Answer 6

I messed up, sorry, I though it is all 65...

Answer 7

@Nurali is right :)

Answer 8

awesome. thanks for helping

Answer 9

Anytime.

Answer 10

thanks nurali

Answer 11

so we just reversed the formula haha