Answer:
[tex]\cos(69)[/tex]
Step-by-step explanation:
We will use the co-function identity for sine, where:
[tex]\sin(x)=\cos(90-x)[/tex]
Since sin(21)=0.358=cos(x). This means that:
[tex]21=90-x[/tex]
Solve for x. Add x to both sides:
[tex]x+21=90[/tex]
Subtract 21 from both sides:
[tex]x=69\textdegree[/tex]
Hence:
[tex]\sin(21)=\cos(69)\approx0.358[/tex]
