Question

express as a single fraction the exact value of sin75

Answer 1

sin(75) = sin(45 + 30) right? What's the angle addition formula?

Answer 2

sin(a+b)=sinAcosB+cosAsinB

Answer 3

Indeed it is. So apply that to this problem, and what do you get?

Answer 4

where do i get the value of cos?

Answer 5

\[ \sin(45) = \cos(45) = \frac{1}{\sqrt{2}} \]
\[\cos(30) = \frac{\sqrt{3}}{2}\]
\[\sin(30) = \frac{1}{2} \]

Answer 6

so the answer is 1/2?

Answer 7

It should be
\[ \frac{\sqrt{3}+1}{2\sqrt{2}} \]