If sin y = sin 3t and x = sin t, then \(\frac{dy}{dx}\) =
\(\frac{3}{\sqrt4-x^2}\)
\(\frac{3}{\sqrt1-x^2}\)
\(\frac{1}{\sqrt4-x^2}\)
\(\frac{-1}{\sqrt4 - x^2}\)
The correct option is (B) \(\frac{3}{\sqrt1-x^2}\)
In a triangle \(ABC\), \(\displaystyle \frac{a(rr_1+r_2r_3)}{r_1-r+r_2r_3} =\;?\)
For \( n \in \mathbb{N} \), the largest positive integer that divides \( 81^n + 20n - 1 \) is \( k \). If \( S \) is the sum of all positive divisors of \( k \), then find \( S - k \).