CPM Homework Help : INT3 Problem 11-72

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

Hint:

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

Answer:

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