Solve cos(-60^o)-tan135^o-:tan315^o +cos660^o?

1 Answer
Shwetank Mauria
Jul 3, 2016

cos(-60^o)-tan135^o-:tan315^o +cos660^o=0

Explanation:

To solve cos(-60^o)-tan135^o-:tan315^o +cos660^o

we make use of cos60^o=1/2 and tan45^o=1 and also the identities cos(-A)=cosA and tan(360^o-A)=tan(180^o-A)=-tanA.

Hence cos(-60^o)-tan135^o-:tan315^o +cos660^o

= cos60^o-tan(180^o-45^o)-:tan(360^o-45^o) +cos(720^o-60^o)

= cos60^o-(-tan45^o)-:(-tan45^o) +cos(-60^o)

= 1/2-(-1)-:(-1) +cos60^o

= 1/2-1+1/2=0

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