# Controlling Angles with Sliders: Ex. 14

- Author:
- Tim Brzezinski

- Topic:
- Angles, Mathematics

## DIRECTIONS:

1) Construct a segment .
2) Select the SLIDER tool. Select ANGLE. Set Min = . Set Max = . Set Increment = .
Hit OK. Slider should be named .
3) Select the ANGLE WITH GIVEN SIZE tool.
Select point

*B*. Then select point*A*(vertex of soon-to-appear angle). Then, where it says , delete this and replace with (see menu off to right). Select COUNTERCLOCKWISE. If you do this correctly, you should see a new point*B'*so that . 4) Construct a ray with endpoint B that passes through*B'*. 5 )Select the ANGLE WITH GIVEN SIZE tool. Select point*A*. Then select point*B*. Then, where it says , delete this and replace with (see menu off to right). Select CLOCKWISE. You should see a new point A*'*so that . More directions appear below the applet.6) Construct a ray with endpoint

*A*that passes through*A'*. 7) Plot the point of intersection of the 2 rays you've just constructed in steps (4) & (6). 8) Go to the algebra view (left). Hide the 2 rays, the original segment , and the points*A'*and*B'*. 9) Use the POLYGON tool with vertices*A*,*B*, and the point of intersection of the 2 rays you constructed in step (7).## 10)

Display the length of all sides of this triangle. Move the slider around. What do you notice? What can we conclude about a triangle with 2 congruent angles?

## 11)

What happens if we set ?

When you're done (or if you're unsure of something), feel free to check by watching the quick silent screencast below.