Cos⁴ a - sin⁴a is equal to
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Answer:
cos⁴A = (cos²A)²
sin⁴A = (sin²A)²
cos⁴A - sin⁴A = (cos²A)² - (sin²A)²
( Here we use a^2-b^2 formula)
= ( cos²A + sin²A) (cos²A - sin²A)
= (1)* (cos²A - (1 - cos²A)
= cos²A - 1 + cos²A
= 2 cos²A - 1
Hope it will help you ✌️
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