trigonometry

[r267747]

QUES; PLEASE PROVE THESE EQUATIONS USING "C" "D" AND OTHER FORMULAS:
1.sin10degree+sin20degree+sin40degree+sin50degree=sin70degree+sin80degree
2.4sinA sin(60+A) sin(60-A)=sin3A
3.sin alpha+sin(alpha +2pie/3) +sin(alpha+4pie/3)=0
4.cot4x (sin5x+sin3x)= cotx (sin5x-sin3x)

 

[Deleted member 4993]

QUES; PLEASE PROVE THESE EQUATIONS USING "C" "D" AND OTHER FORMULAS:
1.sin10degree+sin20degree+sin40degree+sin50degree=sin70degree+sin80degree
2.4sinA sin(60+A) sin(60-A)=sin3A
3.sin alpha+sin(alpha +2pie/3) +sin(alpha+4pie/3)=0
4.cot4x (sin5x+sin3x)= cotx (sin5x-sin3x)

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viewtopic.php?f=3&t=36343&p=141509#p141509

".....USING "C" "D" AND OTHER FORMULAS" - what is "C" and "D"?

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