Intro to Trig
Consider the Following..
How many triangles do you see? How do they relate? How do you know?
Now use the slider D to move EF...
Since these triangles are similar, we know that the corresponding sides are in proportion. Look closely at the relationship between FE/EA and CB/BA. What happens to this relationship as you move EF?
What do you think would happen if angle A (theta) changed?