A) \[\tan \alpha \]
B) \[\tan (\pi -\alpha )\]
C) \[\cot \alpha \]
D) \[-\cot \alpha \]
Correct Answer: D
Solution :
Equation of a tangent at \[(a\cos \alpha ,\ a\sin \alpha )\] to the circle \[{{x}^{2}}+{{y}^{2}}={{a}^{2}}\] is \[ax\cos \alpha +ay\sin \alpha ={{a}^{2}}\]. Hence its gradient is\[-\frac{a\cos \alpha }{a\sin \alpha }=-\cot \alpha \].You need to login to perform this action.
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