Question

Is smart do this solve
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Answer 1

Explanation:

Assume 80° should be 180° to have same pattern.

Use reduction formulas and solve:

• 
  `(sin(180+A)+2cos(180+A)cos(A-180))/(2cos^2(360+A)-cos(-A)) =`
• 
  `(-sin(A)+2(-cos(A))(-cos(A)))/(2cos^2(A)-cos(A)) =`
• 
  `(2cos^2(A)-sin(A))/(2cos^2(A)-cos(A))`

As given, it simplifies to the above fraction.

If the sin was cos then the final result would be 1 as both numerator and denominator would be equal.