prove a trigonometric equation: If √2cosA = cosB + cos³B and √2sinA = sinB - sin³B, then...

[fesk]

If √2cosA = cosB + cos³B and √2sinA = sinB - sin³B. Then, Prove that, sin(A - B) = ±(1/3)

 

[stapel]

If √2cosA = cosB + cos³B and √2sinA = sinB - sin³B. Then, Prove that, sin(A - B) = ±(1/3)

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[khansaheb]

If √2cosA = cosB + cos³B and √2sinA = sinB - sin³B. Then, Prove that, sin(A - B) = ±(1/3)

First write sin(A-B) in terms of sin(A), sin(B), cos(A) & cos(B).

Then replace cos(A) and sin(A) using given relations. ......... continue..........