IM Geo.2.9 Lesson: Side-Side-Side Triangle Congruence
Construct a triangle with the given side lengths using the applet below.
Side lengths:
Can you make a triangle that doesn’t look like anyone else’s?
Priya was given this task to complete:
Use a sequence of rigid motions to take STU onto GHJ. Given that segment ST is congruent to segment GH, segment TU is congruent to segment HJ, and segment SU is congruent to segment GJ. For each step, explain how you know that one or more vertices will line up.
Help her finish the missing steps in her proof:
Now, help Priya by finishing a few-sentence summary of her proof. “To prove 2 triangles must be congruent if all 3 pairs of corresponding sides are congruent . . . .”
It follows from the Side-Side-Side Triangle Congruence Theorem that, if the lengths of 3 sides of a triangle are known, then the measures of all the angles must also be determined. Suppose a triangle has two sides of length 4 cm.
Use a ruler and protractor to make triangles and find the measure of the angle between those sides if the third side has these other measurements.
Do the side length and angle measures exhibit a linear relationship?
Quadrilateral ABCD is a parallelogram.
By definition, that means that segment is parallel to segment , and segment is parallel to segment .
Prove that angle is congruent to angle .