Question

√3(sin^4 15- cos^4 15)

Answer 1

$sqrt{3}(sin^4 15- cos^4 15)=sqrt{3}(sin^2 15- cos^2 15)(sin^2 15+ cos^2 15)=$

$=sqrt{3}(sin^2 15- cos^2 15)=-sqrt{3}cos30=-frac{3}{2}$