Question: 14. Calculate the measure of $\angle BEC$ to the nearest degree.
B
E
A
C
4.6 m
3.7 m
39^\circ
\angle \text{ at } C, \text{ with } EC \perp BA; \text{ triangle } BEC \text{ is on the left and triangle } ECA \text{ is on the right.
1. **State the problem:** We need to find the measure of $\angle BEC$ in the given figure where $EC$ is perpendicular to $BA$, $\angle C = 39^\circ$, and the sides $BE = 4.6$ m and $EA = 3.7$ m.
2. **Analyze the figure and given information:** Since $EC$ is perpendicular to $BA$, $\angle ECA = 90^\circ$. Triangle $ECA$ is right-angled at $C$.
3. **Use triangle $ECA$ to find $EC$:**
Given $\angle C = 39^\circ$ and $EA = 3.7$ m, in right triangle $ECA$:
$$\cos(39^\circ) = \frac{EC}{EA} \implies EC = EA \times \cos(39^\circ)$$
Calculate:
$$EC = 3.7 \times \cos(39^\circ) \approx 3.7 \times 0.7771 = 2.8753 \text{ m}$$
4. **Use triangle $BEC$ to find $\angle BEC$:**
In triangle $BEC$, we know:
- $BE = 4.6$ m
- $EC \approx 2.8753$ m
- $\angle ECB = 90^\circ$ (since $EC \perp BA$)
We want $\angle BEC$, which is the angle at $E$ opposite side $BC$.
5. **Calculate $\angle BEC$ using tangent:**
$$\tan(\angle BEC) = \frac{EC}{BE} = \frac{2.8753}{4.6} \approx 0.6249$$
6. **Find $\angle BEC$:**
$$\angle BEC = \tan^{-1}(0.6249) \approx 32^\circ$$
**Final answer:**
$$\boxed{32^\circ}$$