Observe o trapézio ABCD, com alguns dados fornecidos na figura:
Aplicando a lei dos cossenos no triângulo BEC , a medida de \(\overline{BC}\) , em centímetros, será
(A) \(\dfrac{\sqrt{25+32 \cos^2 40^{\circ}-40\sqrt{2}\cdot \cos 40^{\circ} \cdot \text{sen} 85^{\circ} }}{\cos 40^{\circ}}\)
(B) \(\dfrac{\sqrt{25+32\cos^2 40^{\circ}-40\sqrt{2}\cdot \text{sen} 40^{\circ} \cdot \cos 85^{\circ} }}{\text{sen} 40^{\circ}}\)
(C) \(\dfrac{\sqrt{25+32 \text{sen}^2 40^{\circ}-40\sqrt{2}\cdot \text{sen} 40^{\circ} \cdot \cos 85^{\circ} }}{\text{sen} 40^{\circ}}\)
(D) \(\dfrac{\sqrt{25+32\cos^2 40^{\circ}-40\sqrt{2}\cdot \cos 40^{\circ} \cdot \cos 85^{\circ} }}{\cos 40^{\circ}}\)
(E) \(\dfrac{\sqrt{25+32\cos^2 40^{\circ}-40\sqrt{2}\cdot \text{sen} 40^{\circ} \cdot \cos 85^{\circ} }}{\cos 40^{\circ}}\)