How do you simplify sin4(x)−cos4(x)−sin2(x)+cos2(x) ?
1 Answer
Oct 21, 2016
Explanation:
Use:
a2−b2=(a−b)(a+b)
sin2(x)+cos2(x)=1
as follows:
sin4(x)−cos4(x)−sin2(x)+cos2(x)
=(sin4(x)−cos4(x))−(sin2(x)−cos2(x))
=(sin2(x)−cos2(x))(sin2(x)+cos2(x))−(sin2(x)−cos2(x))
=(sin2(x)−cos2(x))(sin2(x)+cos2(x)−1)
=(sin2(x)−cos2(x))(1−1)
=0