Тригонометрия помогите

$\dfrac{1 - \text{tg}^{2} 178^{\circ}}{\text{tg}^{2} 178^{\circ} + 1} = \dfrac{1 - \text{tg}^{2} (180^{\circ} - 2^{\circ})}{\text{tg}^{2} (180^{\circ} - 2^{\circ}) + 1} = \dfrac{1 - \text{tg}^{2} 2^{\circ}}{\text{tg}^{2} 2^{\circ} + 1} = \dfrac{1 - \left(\dfrac{\sin 2^{\circ}}{\cos 2^{\circ}} \right)^{2}}{\left(\dfrac{\sin 2^{\circ}}{\cos 2^{\circ}} \right)^{2} + 1} =$

$= \dfrac{1 - \dfrac{\sin^{2} 2^{\circ}}{\cos^{2} 2^{\circ}}}{\dfrac{\sin^{2} 2^{\circ}}{\cos^{2} 2^{\circ}} + 1} = \dfrac{\dfrac{\cos^{2} 2^{\circ} - \sin^{2}2^{\circ}}{\cos^{2}2^{\circ}} }{\dfrac{\sin^{2}2^{\circ} + \cos^{2}2^{\circ}}{\cos^{2}2^{\circ}} } = \dfrac{\cos^{2}2^{\circ} - (1 - \cos^{2}2^{\circ})}{1} =$