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`        cos 43o + cos 29o - sin 11o - cos 65o is equal toa > sin 7ob > cos 36oc > sin 83od > none of thesecorrect answer - c want proper explanation`
one year ago

pranav ubarhande
39 Points
```							Sin 11 will be equal to cos 79.now the whole expression will be cos 43+cos 29 - cos 79-cos65.now use formula"cos c-cos d = 2 sin (c+d)/2 into sin ( d- c)/2" on 1st and 4th term and then on 2nd and 3rd term.Now this whole expression will be converted into2×sin108/2 ×sin 22/2 +2× sin 108/2×sin 50/2Taking sin 54 common, 2sin54(sin11+ sin25).Now again use formula for bracket ,"Sin c+sin d =2sin (c+d)/2 into cos(c-d)/2"Now the expression will be converted into 2sin 54(2sin 18 cos(-7))=2sin54(2sin18 cos7)as cos -x= cos =4×sin54 sin 18 cos 7Sin 54=(root5+1)/4, sin 18=(root5-1)/4 put values Hence =cos7=sin 83 as "cos a=sin 90- a" hence proved sir
```
one year ago
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### Course Features

• 31 Video Lectures
• Revision Notes
• Test paper with Video Solution
• Mind Map
• Study Planner
• NCERT Solutions
• Discussion Forum
• Previous Year Exam Questions