sin 750 =
2−√32
√3+12√2
√3−1−2√2
√3−12√2
sin75∘=sin(90∘−15∘)=cos15∘=cos(45∘−30∘)
= √3+12√2.
y = sin21500∘+4sin4750∘−4sin2750∘cos2750∘4−sin21500∘+4sin2750∘ Find the value of 9y.
If y=sin21500∘+4sin4750∘−4sin2750∘cos2750∘4−sin21500∘−4sin2750∘. Then the value of 9y is ___