8.4 Proportionality Theorems

Geogebra Investigation 1)Draw a triangle ABC. 2)Place point D on side AB. 3)Draw a line through point D parallel to BC. 4)Place E on the intersection that line and AC. 5)Find the lengths of AD, BD, AE, CE using the length tool (8 th from left). 6)Find the ratio of AD to BD and AE to CE. 7)Adjust the triangle with the arrow tool and repeat step 5 until you can make a conjecture.

1)Construct a triangle ABC. 2)Construct an angle bisector for angle B. 3)Place point D where the angle bisector intersects with side AC. 4)Find the lengths of AD, DC, BA and BC. 5)Find the ratio of AD to DC and BA to BC. 6)Adjust the triangle with the arrow tool and repeat step 5 until you can make a conjecture.

Try this problem on your own…

Try this on your own…

Guided Practice