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```
Prove that , (sinX) 3 × sin3X + (cosX) 3 × cos3X =(cos2X) 3

```
2 years ago

Susmita
425 Points
```							Use the formulasin3x=(3sinx-sin3x)/4and cos3x=(3cosx+cos3x)/4also cos3(2x)=(3cos2x+cos6x)/4Put the first two formula in the given expression.you will get(3sinxsin3x-sin23x+3cosxcos3x+cos23x)/4Put 3sinxsin3x+3cosxcos3x=cos(3x-x)=cos2xAnd cos23x-sin23x=cos(2.3x)=cos6x.and see you will get the ans.
```
2 years 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