The line $x\cos \alpha + y\sin \alpha = p$ will be a tangent to the conic $\frac{{{x^2}}}{{{a^2}}} + \frac{{{y^2}}}{{{b^2}}} = 1$, if
The line $x\cos \alpha + y\sin \alpha = p$ will be a tangent to the conic $\frac{{{x^2}}}{{{a^2}}} + \frac{{{y^2}}}{{{b^2}}} = 1$, if
- A
${p^2} = {a^2}{\sin ^2}\alpha + {b^2}{\cos ^2}\alpha $
- B
${p^2} = {a^2} + {b^2}$
- C
${p^2} = {b^2}{\sin ^2}\alpha + {a^2}{\cos ^2}\alpha $
- D
None of these
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