Buktikan identitas Cotan A - tan A = 2 cos kuadrat A-1 per sin A × cos A

(tan A - cot a)/(tan A + Ccot A)=(sin A/cos A -cos A/sin A) / (sin A/cos A+cos A/sin A) KALIKAN SIN Acos A/sin Acos A

(sin2 A-cos2 A) /(sin2 A + cos2 A)={1-2 cos2 A
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