Download Brianne Pizzigoni Similar Triangles Mathematics Grade 3

Brianne Pizzigoni
Similar Triangles
Mathematics
Grade 3
FORWARD
Click on each the following triangles to learn
about similar triangles!
1
5
2
5
6
3
4
7
AFTER CLICKING ON
EACH TRIANGLES CLICK
ON THE STAR FOR YOUR
FOLLOW UP MULTIPLE
CHOICE QUESTION 
8
Ratio
CLICK HERE
AFTER READING
• The first thing you need to know about similar triangles is that Similar
Triangles ARE NOT congruent. The sides of the triangle are in
ratio/proportion. That means that one triangle is either sized up or down to
form another similar triangle.
• In triangle Number 5 you will see an example problem on how to solve a
ratio question concerning similar triangles.
SSS
• The SSS property states that when three sides of one triangle are in
proportion to three sides of another triangle, than those two triangles are
similar.
• In Triangle number 6 you will see an example of the SSS Property.
CLICK HERE AFTER
READING
SAS
• The SAS property states that when two sides of one triangle are in
proportion to two sides of another triangle AS WELL AS the angle in
between those two sides are congruent to each other, than the two triangles
are similar.
• In Triangle number 7 you will see an example of the SAS Property.
CLICK HERE
AFTER
READING
AAA
• The AAA property states that when three angles of one triangle are
congruent to three angles in another triangle, than those two triangles are
similar.
• In Triangle number 8 you will see an example of the AAA Property.
CLICK HERE
AFTER
READING
Example of Ratio
The picture above shows an example of how to use the ratio rule to determine similar triangles. In this example the two
triangles are similar. This means that side BA corresponds to side YX, side BC corresponds to side YZ, and side AC
corresponds to side XZ. This also means that the ratio of these are equal. The ratio of BA/YX equals the ratio of
BC/YZ which equals the ratio of AC/XZ. The ratio is ½. You can use this concept to solve missing sides of triangles
and to determine if two triangles are similar using the SSS property.
CLICK HERE
AFTER
READING
Example of SSS
CLICK HERE
AFTER
READING
Using your knowledge of the Ratio Rule you would be able to determine if these two triangles are similar.
Side MK is to side PR, side ML is to side PQ, and Side KL is to side QR. That means that in order for these
two triangles to be similar the following must be true.
MK/PR = KL/QR = ML/PQ OR
10/12 = 20/24 = 15/18
THE TRIANGLES ARE SIMILAR.
RATIO = 5/6
Example of SAS
You can determine that these two triangles are similar using the SAS Property. You can see that the two given angles
are congruent. Also the two sides 4 and 10 of the first triangle are in proportion of the second triangle with sides 2
and 5. That means that 4/2 = 10/5. The two triangles have a ration of ½ or 2
CLICK HERE
AFTER
READING
Example of AAA
CLICK HERE
AFTER
READING
You can determine that these two triangles are similar by simply looking at the triangles. You can see that the three
angles in the one triangle are congruent to the angles in the other triangle.
Keep in mind, if you were only given the two angles of each triangle you would still be able to determine that these
two triangles are similar because the angles within a triangle have to equal 180 degrees.
MULTIPLE CHOICE QUESTION
Only using the given information, which property proves that these two
triangles are similar?
A- AAA
B- SAS
C- SSS
AAA
• INCORRECT; Only one angle of the triangles are given so you can not
determine whether the two triangles are similar by this property.
CLICK HERE TO TRY
AGAIN
SAS
• CORRECT!!! The two sides of the one triangle are in proportion AS WELL
AS the angle in between those two sides are congruent.
CLICK HERE
SSS
• INCORRECT; only two sides of the triangle are given.
CLICK HERE TO TRY
AGAIN
CONGRADULATIONS
• YOU HAVE NOW COMPLETED THE LESSON. PLEASE CLICK ON
THE ICON BELOW FOR THE NEXT STUDENT.