Question

Sin² 75° - Sin² 15°​

Answer 1

sin^2(45+30)-sin^2(45-30)

[sin (45+30)+sin (45-30)][sin (45+30)-sin (45-30)]

{ 2sin45cos30 }{2cos45sin30}

= 4sin45×sin30×cos45×cos30

= (4×1/2× 1/2×root3/2)

= root3/2 =sin60=cos30