ANSWER
D) sin Y
EXPLANATION
The given triangle is a right triangle.
This implies that that:
[tex]x + y = 90 \degree[/tex]
Then we have
[tex]y= 90 - x[/tex]
Recall that
[tex] \cos(x) = \sin(90 - x) [/tex]
But
[tex]90 - x = y[/tex]
When we do the substitution, we get,
[tex] \cos(x) = \sin(y) [/tex]
Therefore cos(x) is a equivalent to sin(y).
The correct answer is D.
