If \( \sqrt{3}tan\theta =3sin\theta ,\) then the value of \( si{n}^{2}\theta -co{s}^{2}\theta \) is (A) \( \frac{1}{2}\) (B) \( \frac{1}{3}\) (C) \( \frac{1}{4}\) (D) \( \frac{1}{5}\)
If a and b are real number such that \( acos\theta +bsin\theta =4\) and \( asin\theta -bcos\theta =3\), then \( {(a}^{2}+{b}^{2})\) is (A) 7 (B) 12 (C) 25 (D) \( \sqrt{12}\)
If A is an acute angle and \( tanA=\frac{5}{12}, \)the value of case A is (A) \( \frac{11}{5}\) (B) \( \frac{13}{5}\) (C) \( \frac{16}{5}\) (D) \( \frac{17}{5}\)
If \( \alpha \) and \( \beta \) are the roots of the quadratic equation \( 4{x}^{2}+2x-1=0\) then the value of \( \sum _{r=1}^{\infty }\left({\alpha }^{r}+{\beta }^{r}\right)\) is: (a) \( 2\) (b) \( 3\) (c) \( 6\) (d) \( 0\)