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For given question Sin160 cos 110+sin 250 cos 340+tan 110 tan 340=k value of k=?

For given question Sin160 cos 110+sin 250 cos 340+tan 110 tan 340=k value of k=?

Grade:12

1 Answers

Arun
25750 Points
5 years ago
sin(160) cos(110)  +  sin(250) cos(340)  +  tan(110) tan(340) 

=  sin(160) cos(110)  +  sin(250) cos(340)  +  [sin(110) sin(340) ] ⁄ [ cos(110) cos(340)  ] 

 ... based on the symmetry of the sine and cosine functions the following 
 ... substitutions can be made so all of the angles are the same. 

=  sin(20) (- sin(20))  +  (- cos(20)) cos(20)  +  [cos(20) (- sin(20)) ] ⁄ [ (- sin(20)) cos(20)  ] 

=  - sin²(20)  –  cos²(20)  +  [cos(20) (- sin(20)) ] ⁄ [ (- sin(20)) cos(20)  ] 

=  -  [sin²(20) + cos²(20) ]  +  1  ... identity: sin²(x) + cos²(x) = 1 

=  - 1  +  1 

=  0

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