A triangle is completely determined if we know 2 "sides" and the size of the angle between them.
--This is the DIY (do it yourself) exercise. At any time if want to review the directions, click on the Remind Me button below to get to the previous exercise with complete directions. However, when you come back you will have to start over.
Start: First click and drag the sliders to any values you want
(probably α<10° or α>170° is not a good plan...)
Now - as we did in the previous exercise:
(1) make a side AB of length "a",
(2) make an angle at A of size "α" and then
(3) do the construction to find the third point of the triangle
Finally connect the three points of your triangle.
End 1: Select the 'Move' tool. Click and drag the points A and B to check that the triangle always remains the same (congruent) when the sides and angle are fixed.
End 2: Click and drag the sliders for the sides and angles. Check that each time a specific triangle is made.
- Now click on the Next button to do see that you really do need 2 sides and an angle to determine the triangle.
Authors: LFS-RF, Created with GeoGebra