Question

sin^215- Cos²15
Pls tell me the answer w/ working .thank you

Answer 1

Answer:

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

Step-by-step explanation:

${ \sin}^{2}15 - { \cos}^{2}15$

$= { \sin }^{2}15 - 1 + { \sin}^{2}15$

$= 2 { \sin}^{2} 15 - 1$

$= - ( 1 - 2{ \sin}^{2}15 )$

$= - ( \cos(2 \times 15))$

$= - (cos30)$

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