Answer:
Side x is adjacent to 30° angle.
Correct method is:
- cos 30° = x/15 ⇒ x = 15*cos 30° ⇒ x = 12.99
Diego is correct and Steven is wrong.
- when finding sine consider the opposite side to the angle, not hypotenuse
- when finding cosine consider adjacent side to the angle, not hypotenuse