Triangle between parallel lines
Instructions
1) Use the "Angle" tool to measure all 7 angles pictured (∠CDE, ∠EDF, ∠FDG, ∠HED, ∠FED, ∠DFE, and ∠IFD). Pro tip - if you click on the angle tool and then click on the points found in the name of the angle in order, it will measure the angle. If the wrong angle is measured, try clicking the points in the opposite direction.
2) Use the "Distance or Length" tool to measure segments DE, DF and EF. You can either click on the middle of the segment, or if that doesn't work, click on the two endpoints of the segment.
3) Use the "Area" tool to find the area of the triangle.
If you are having any problems following the instructions, watch the video below the Geogebra applet