### Home > PC > Chapter 4 > Lesson 4.1.2 > Problem4-25

4-25.

Given: $\text{cos }θ =\frac { 3 } { 5 }$.

1. Draw a right triangle and place values on the sides so that $\text{cos }θ =\frac { 3 } { 5 }$.

2. Draw a unit circle diagram to clearly show the TWO possible positions for $θ$.

3. Use the Fundamental Pythagorean Identity or a right triangle to find all possible values for $\text{sin }θ$.

4. Find all possible values for $\text{tan }θ$.

It must be a $3-4-5$ triangle because of the Pythagorean Theorem. Determine the two sine values.

$\tan(\theta)=\frac{\text{opposite}}{\text{adjacent}}=\frac{\pm4}{3}=\pm\frac{4}{3}$