Answer:
4th Option
Explanation:
When we look for side x, we have multiple ways:
cos60° = 10/x
x = 10/cos60°
sin30° = 10/x
x = 10/sin30°
sin60° = 15/x
x = 15/sin60°
cos30° = 15/x
x = 15/cos30°
Out of these choices, only the 4th Option is present, so that is our answer.