Question

cos^4A-sin^4A+1=2cos^2A​

Answer 1

Answer:

LHS,

cos⁴A - sin⁴A +1

= (cos²A-sin²A)(cos²A + sin²A)+1

= (cos2A)(1) +1

= 1 + cos2A

= 2cos²A

Step-by-step explanation:

formula used

1. sin²@ + cos²@ = 1

2. cos²@ - sin²@ = cos2@

3. a² - b² = ( a +b)(a -b)

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