What is the value of (Quant Trigo #01)

What is equal to?

  1. cos2 A - sin2 A
  2. cos A - sin A
  3. 1
  4. 2

Answer

a2 - b2 = (a - b)(a + b)

cos4 A - sin4 A = (cos2 A - sin2 A)(cos2 A + sin2 A) = (cos2 A - sin2 A)

Thus, the numerator and the denominator will cancel each other. The answer will be 1.

The correct option is C.