### Home > INT3 > Chapter 11 > Lesson 11.2.2 > Problem11-72

11-72.

The sine of obtuse angle $A$ is $\frac { 3 } { 10 }$. What is the tangent of angle $A$?

First use $\text{sin}^{2}A + \text{cos}^{2}A = 1$ to find $\text{cos}A$.
Note that $A$ is in the second quadrant.

$\text{tan}A=\frac{-3}{\sqrt{91}}$