Question

how to prove it ? step by step

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Answer 1

Step-by-step explanation:

[ Refer to the attachment ]

• Sin²x + Cos²x = 1

• $\tan(x) = \frac{ \sin(x) }{ \cos(x) }$

• ( a + b + c )² = a² + b² + c² + 2ab + 2bc + 2ca

• Multiplying by the conjugate of the numerator in 4th step !!