Question

Sin² 75° - Sin² 15°​

Answer 1

$\sin {}^{2} (75°) - \sin {}^{2} (15°)$

$= \sin {}^{2} (90° - 15°) - \sin {}^{2} (15°)$

$= \cos {}^{2} (15°) - \sin {}^{2} (15°)$

$= \cos(2(15°))$

$= \cos(30°)$

$= \frac{ \sqrt{3} }{2}$