How do you solve the following, please show work.

If sin(theta)=0.3, find sin (theta+pi)

Question

How do you solve the following, please show work.  

If sin(theta)=0.3, find sin (theta+pi)

freckles · Answer

$$\sin(\theta+\pi)=\sin(\theta) \cos(\pi)+\sin(\pi) \cos(\theta)=?$$

freckles · Answer

$$\text{So I bet you you are having troubles with the } \cos(\theta) \text{ part } $$
Am I right?

freckles · Answer

We are given $$\sin(\theta)=\frac{3}{10}$$
Draw a right triangle giving measurement 10 to the hyp and measurement 3 to the opp

freckles · Answer

Use the Pythagorean thm to find the adj side :)

freckles · Answer

$$\text{Then boom you can find } \cos(\theta)$$

anonymous · Answer

looking at the graph of sin(x) (or using the expansion of sin(a + b)) you can see that sin(x + pi) = -sin(x), just another way to approach it