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MATU • Trigonometria
MATU_TRI_065
Guía de ejercicios
Enunciado
Calcule el valor de: $F = 3 \tan C + 4 \tan B$, si $A + B + C = \pi$, y además se cumple:
$$\tan\left(\frac{A}{2}\right) = 3 \tan\left(\frac{B}{2}\right) = 2 \tan\left(\frac{C}{2}\right)$$
$$\tan\left(\frac{A}{2}\right) = 3 \tan\left(\frac{B}{2}\right) = 2 \tan\left(\frac{C}{2}\right)$$
Solución Paso a Paso
1. Datos del problema:
2. Fórmulas/Propiedades:
3. Desarrollo paso a paso:
$$(6k)(2k) + (2k)(3k) + (3k)(6k) = 1 \implies 12k^2 + 6k^2 + 18k^2 = 1$$
$$36k^2 = 1 \implies k = 1/6$$
$\tan(B/2) = 2(1/6) = 1/3$
$\tan(C/2) = 3(1/6) = 1/2$
$\tan B = \frac{2(1/3)}{1 - (1/3)^2} = \frac{2/3}{8/9} = \frac{3}{4}$
$\tan C = \frac{2(1/2)}{1 - (1/2)^2} = \frac{1}{3/4} = \frac{4}{3}$
$F = 3(4/3) + 4(3/4) = 4 + 3 = 7$
4. Resultado final:
$$F = 7$$
- $A + B + C = 180^\circ$
- $\tan(A/2) = 3\tan(B/2) = 2\tan(C/2)$
2. Fórmulas/Propiedades:
- En un triángulo: $\tan \frac{A}{2}\tan \frac{B}{2} + \tan \frac{B}{2}\tan \frac{C}{2} + \tan \frac{C}{2}\tan \frac{A}{2} = 1$
- $\tan \theta = \frac{2\tan(\theta/2)}{1 - \tan^2(\theta/2)}$
3. Desarrollo paso a paso:
- Sea $k$ una constante tal que: $\tan(A/2) = 6k$, $\tan(B/2) = 2k$, $\tan(C/2) = 3k$.
- Aplicamos la propiedad de la suma de productos de tangentes medios:
$$(6k)(2k) + (2k)(3k) + (3k)(6k) = 1 \implies 12k^2 + 6k^2 + 18k^2 = 1$$
$$36k^2 = 1 \implies k = 1/6$$
- Hallamos los valores individuales:
$\tan(B/2) = 2(1/6) = 1/3$
$\tan(C/2) = 3(1/6) = 1/2$
- Calculamos $\tan B$ y $\tan C$:
$\tan B = \frac{2(1/3)}{1 - (1/3)^2} = \frac{2/3}{8/9} = \frac{3}{4}$
$\tan C = \frac{2(1/2)}{1 - (1/2)^2} = \frac{1}{3/4} = \frac{4}{3}$
- Calculamos $F$:
$F = 3(4/3) + 4(3/4) = 4 + 3 = 7$
4. Resultado final:
$$F = 7$$