(iv) sinθ−cosθtanθ2cosθ+sinθtanθ2=tanθ2\dfrac{\sin\theta - \cos\theta \tan\dfrac{\theta}{2}}{\cos\theta + \sin\theta \tan\dfrac{\theta}{2}} = \tan\dfrac{\theta}{2}cosθ+sinθtan2θsinθ−cosθtan2θ=tan2θ