ANSWER
[tex]\sin(40) \degree = 0.6428[/tex]
EXPLANATION
The sine and cosine ratios are complementary.
This means that:
[tex] \cos(x \degree) = \sin(90 - x) \degree[/tex]
We were given that,
cos(50°)=0.6428
We want to find the sine of the complement of this angle.
[tex] \cos(50\degree) = \sin(90 -5 0) \degree[/tex]
[tex]\cos(50\degree) = \sin(40) \degree[/tex]
This implies that,
[tex] \sin(40) \degree = 0.6428[/tex]
