buktikan identitas trigonometri cos^2 A - sin^2 A = 1-tan^2 A / 1+tan^2A
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buktikan identitas trigonometri cos^2 A - sin^2 A = 1-tan^2 A / 1+tan^2A
1 Jawaban
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1. Jawaban Anonyme
Trigonometri.
[tex]\displaystyle \frac{1-\tan^2 A}{1+\tan^2 A}\\ =\frac{1-\frac{\sin^2 A}{\cos^2 A}}{1+\frac{\sin^2 A}{\cos^2 A}}\\ =\frac{\cos^2 A-\sin^2 A}{\cos^2 A+\sin^2 A}\\ =\cos^2 A-\sin^2 A[/tex]
Terbukti.