**Example 3: **John is standing on a hill on a 15m distance from the helicopter. The ship watches the helicopter on a 60° angle and with a distance of 10 meters. Find how far is John from the ship?

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**Solution: **Based on the figure above to find how far is John from the ship we can use the** Cosine Law:**

$\displaystyle {{c}^{2}}={{a}^{2}}+{{b}^{2}}-2ab\cdot cosC$

x² = 15² + 10² – 2 ⋅ 15 ⋅ 10 ⋅ cos60°

x² = 225 + 100 – 300 ⋅ $ \displaystyle \frac{1}{2}$

x² = 325 – 150

x² = 175

x = $\displaystyle \sqrt{{175}}$

x $ \displaystyle \approx 13.2$

**John is ****approximately 13.2 m from the ship**