Q.If \( \cos\theta = p \) and \( \cot\theta = q \), then which of the following relationships is true? (a) \(\cfrac{1}{p^2}+\cfrac{1}{q^2}=1\) (b) \(\cfrac{1}{p^2}-\cfrac{1}{q^2}=1\) (c) \(\cfrac{1}{p^2}-\cfrac{1}{q^2}=0\) (d) \(\cfrac{1}{q^2}+\cfrac{1}{p^2}=1\)
Answer: B
Given: \( \cos\theta = p \) ⇒ \( \sec\theta = \frac{1}{p} \) ⇒ \( \sec^2\theta = \frac{1}{p^2} \) Also, \( \cot\theta = q \) ⇒ \( \tan\theta = \frac{1}{q} \) ⇒ \( \tan^2\theta = \frac{1}{q^2} \) We know: \( \sec^2\theta - \tan^2\theta = 1 \) ⇒ \( \frac{1}{p^2} - \frac{1}{q^2} = 1 \)
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