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`        I did not understand how to solve these three questions.....................`
11 months ago

## Answers : (2)

1673 Points
```							For the first question note that arguments inside sine are in AP. so use the formula for its summation and you will get zero.Just use sin α + sin (α + β) + sin (α + 2β) + … to n terms = (sin (nβ/ 2))/ (sin (β/ 2)). sin (α + (n-1)β/2)
```
11 months ago
1673 Points
```							For third question, use the identitysinx*sin(60-x)*sin(60+x)= (sin3x)/4Put x=6sin6sin66sin54=sin18/4….(1)Put x=18sin18sin42sin78= sin54/4....(2)Multiply (2) and (1)sin6sin66sin78sin42= 1/16
```
11 months ago
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### Course Features

• 731 Video Lectures
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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