Question

What is `(11pi)/6` in degrees and hence find `cos((11pi)/6)`?

Answer 1

`cos((11pi)/6)=sqrt3/2`

Explanation:

As `pi` radians are equal to `180^@`

`1` radians are equal to `180^@/pi`

`(11pi)/6` radians are `(cancel(180)30^@)/cancelpixx(11cancelpi)/(cancel6^1)`

= `30^@xx11=330^@`

and `cos((11pi)/6)=cos330^@`

= `cos(360^@-30^@)`

= `cos(-30^@)`

= `cos30^@`

= `sqrt3/2`