Angle between two parallel lines
In the animation below, the two thick black lines at the top and bottom are parallel. Slide the "Slide Me!" slider to help you visualize how to solve problems like ones like the one below.
In the example below, by using an imaginary 3rd parallel line to the other two lines, you can visualize how to combine the two given angles to find the unknown. You can move around the vertex of the angle.
