From the given right triangle what is the value of $3 \sin^2 \varphi \, \sec \varphi$ in terms of $x$.

From the given right triangle what is the value of $3 \sin^2 \varphi \, \sec \varphi$ in terms of $x$.

basic_012-right-triangle.gif

 

A. $\dfrac{x}{\sqrt{x^2 + 9}}$ C. $\dfrac{x^2 + 9}{\sqrt{x^2 - 9}}$
B. $\dfrac{9}{\sqrt{x^2 + 9}}$ D. $\dfrac{x^2}{\sqrt{x^2 + 9}}$

Solution