cos 2A in Terms of tan A

We will learn how to express the multiple angle of cos 2A in terms of tan A.

Trigonometric function of cos 2A in terms of tan A is also known as one of the double angle formula.

We know if A is a number or angle then we have,

cos 2A = cos² A  -  sin² A

cos 2A = \(\frac{cos^{2} A - sin^{2} A}{cos^{2} A}\) ∙ cos² A

⇒ cos 2A = cos² A (1 - tan² A)

⇒ cos 2A =  \(\frac{1}{sec^{2} A}\)(1 - tan² A)

⇒ cos 2A = \(\frac{1 - tan^{2} A}{1 + tan^{2} A}\)

● Multiple Angles

• sin 2A in Terms of A
• cos 2A in Terms of A
• tan 2A in Terms of A
• sin 2A in Terms of tan A
• cos 2A in Terms of tan A
• Trigonometric Functions of A in Terms of cos 2A
  
• sin 3A in Terms of A
• cos 3A in Terms of A
• tan 3A in Terms of A
• Multiple Angle Formulae

11 and 12 Grade Math

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