If `p=sin(989^(@))cos(991^(@))`, then which one of the following is correct ?

Options

A. p is finite and positive
B. p is finite and negative
C. p =0
D. p is undefined

Answer

B

Explanation

Given , p `=sin(989^(@))cos(991^(@))`
Which can be written as
`=sin(1080^(@)-91)cos(1080^(@)-89^(@))`
`=-sin91^(@)cos89^(@)`
`=-sin(90^(@)+1^(@))cos89^(@)`
`-=cos1^(@)cos89^(@)`
As `cos1^(@)andcos89^(@)` are positive.
therefore their product is also + ve
Hence, p is finite and negative .