160 likes | 356 Views
Circle the ways that Triangles can be congruent:. SSS SAS SSA AAA AAS. Proving Triangles Similar. Geometry Unit 11, Day 6 Ms. Reed. Similar Triangles. Similar Triangles have congruent angles a similarity ratio between the corresponding sides. The sign for similarity is ~.
E N D
Circle the ways that Triangles can be congruent: • SSS • SAS • SSA • AAA • AAS
Proving Triangles Similar Geometry Unit 11, Day 6 Ms. Reed
Similar Triangles • Similar Triangles have • congruent angles • a similarity ratio between the corresponding sides. • The sign for similarity is ~
In groups of 2: • We will be discovering ways to prove triangles similar. • You will need: calculator ruler protractor scrap paper
Is AA a way to prove triangles similar? • In your groups, each draw a large triangle with a 50° and a 60° angle • Measure the sides of the triangle to the nearest 1/16 • Find the ratio of the corresponding sides • ARE THE TRIANGLES SIMILAR?
Is SAS a way to prove triangles similar? • In your groups, each person draw an angle that is 90° • Using a similarity ratio of ½, proportionally draw the 2 sides that include the angle. • ARE THE TRIANGLES SIMILAR?
Is SSS a way to prove triangles similar? • With a partner, pick the lengths of both triangles with a similarity ratio of ½. **Use a special right triangle to keep in easier** • Draw each of the triangles. **Start with a 90° angle. • Measure the angles of the triangles. • ARE THE TRIANGLES SIMILAR?
Triangle Similarity • We can use AA, SAS, and SSS to prove triangles congruent.
Example 1 • Are these triangles similar? Why? 45 45
Example 2 • Are these triangles similar? Why? 8 8 6 6 9 12
Example 3 • Are these triangles similar? Why? 9 14 7 18
Solving for a missing side: • How are we going to find x?! • Set up a proportion! 5 12 4 x
5 12 4 x Solving for a missing side: What side of one triangle corresponds with what side of the other? 12 = x4 5 x = 15
Example 4 • Find the value of x 9 8 x 6
Homework • Work Packet: Triangle Similarity