Evaluate the following: `cos 80^0cos 20^0+ sin 80^0 sin 20^0`

Evaluate the following: cos 47^0cos 13^0-sin 47^0 sin 13^0

Evaluate the following: cos80^(@)cos20^(@)+sin80^(@)sin20^(@)

Evaluate the following: sin 78^0cos 18^0-cos 78^0sin 18^0

Evaluate the following: sin 36^0cos9^0+cos36^0 sin9^0

Evaluate the following: cos47^(0)cos13^(0)-sin47^(0)sin13^(@)

(2cos 40^0-cos 20^0)/(sin 20^0)=

Evaluate: cos80^@cos20^@+sin80^@sin20^@

Without using trigonometric tables, evaluate each of the following: (sin^2 20^0+sin^2 70^0)/(cos^2 20^0+cos^2 70^0)+(sin(90^0-theta)sintheta)/(tantheta)+(cos(90^0-theta)costheta)/(cottheta)

cos25^(0)cos35^(0)-sin10^(0)sin20^(0) ,