C-09-Q159mediumsingle_mcqcot90∘=?\cot 90^\circ = ?cot90∘=?a000b111c∞\infty∞dundefinedব্যাখ্যাCotangent equals cosθsinθ\dfrac{\cos\theta}{\sin\theta}sinθcosθ, and at 90∘90^\circ90∘ this is 01=0\dfrac{0}{1}=010=0, giving cot90∘=0\cot 90^\circ=0cot90∘=0.