`cos (-870^(@))`=

What is the value of cot (-870^(@)) ?

sin(-870^(@))+cos ec(-660^(@))+tan(-855^(@))+2cot(840^(@))+cos(480^(@))+sec(900^(@)) is equal to

The value of sec(1305^(@))+cot(990^(@))+cos(-780^(@))-cos ec(-765^(@))-sin(-870 is equal to

The value of cos(-89^(@))+cos(-87^(@))+cos(-85^(@))+…+cos(85^(@))+cos(87^(@))+cos(89^(@)) is equal to

cos 20^(@) + cos 40^(@) + cos 60^(@) +...+cos160^(@)+cos 180^(@)=

Prove that cos 80^(@) cos40^(@)+cos40^(@) cos200^(@) +cos200^(@) cos 80^(@) = -3/4

State which of the following is the value of cot(-870^@) ?

A=cos20^(@)cos40^(@)cos60^(@)cos80^(@),B=cos60cos42^(@)cos66^(@)cos78^(@) and C=cos36^(@)cos72^(@)cos108^(@)cos144^(@) then

A=cos 20^(@)cos 40^(@) cos60^(@)cos 80^(@) , B=cos6^(@)cos42^(@)cos66^(@)cos78^(@) and C=cos 36^(@)cos72^(@)cos 108^(@)cos 144^(@) then