What is the value of cos45° sin15° ?
Answer & explanation
Correct answer: option 2
2cosAsinB = sin(A+B) - sin(A-B)
Thus, cos45° sin15° = $\frac{1}{2}(sin(45+15) - sin(45-15))$
= $\frac{1}{2}$sin60° - sin30°
= $\frac{1}{2}\frac{\sqrt{3}}{2} - \frac{1}{2}$
= $\frac{\sqrt{3}-1}{4}$