Copy of SSA Congruence?
Construct a segment with a given length of 4 so that it creates a triangle from point B to the red baseline.
Instructions
1. Find the buttons above the applet. 
2. Click the third button. (should look like a singular line with two points)
3. Click "segment with given length"
4. Click on point B
5. You should now see a pop-up to enter your segment length (4)
6. Click "OK"
7. Using the top row of buttons, click on the cursor again, and click "move," so you can manipulate the triangle
8. Move the new point you created to connect it to the red baseline.