Triangle Similarity Concepts and Problems

This video tutorial covers the concept of similar triangles, which are triangles with the same shape but not necessarily the same size. It explains how to prove triangles are similar using methods like angle-angle, side-side-side, and side-angle-side. The tutorial includes two examples: one on calculating the perimeter of a triangle using similarity and another on determining the height of a tree using shadows and proportions.

What does it mean for two triangles to be similar?

• They have the same side lengths but different angles.

• They have the same size but different shapes.

• They have the same shape but not necessarily the same size.

• They have the same angles but different side lengths.

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CCSS.HSG.SRT.B.5

Which of the following is NOT a method to prove triangles are similar?

• Angle-Side-Angle (ASA)

• Side-Angle-Side (SAS)

• Side-Side-Side (SSS)

• Angle-Angle (AA)

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CCSS.HSG.SRT.A.2

In the Angle-Angle (AA) similarity method, what must be true about the angles?

• Two angles must be congruent.

• No angles need to be congruent.

• All three angles must be congruent.

• One angle must be congruent.

If two triangles are similar and the sides of one triangle are 3, 4, and 5, what is the perimeter of the similar triangle with sides 9, 12, and 15?

• 36 units

• 27 units

• 54 units

• 45 units

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CCSS.7.G.A.1

What is the scale factor between two similar triangles if one triangle has sides 3, 4, and 5, and the other has sides 9, 12, and 15?

• 4

• 2

• 3

• 5

How can you find the perimeter of a similar triangle if you know the scale factor?

• Divide the perimeter of the original triangle by the scale factor.

• Add the scale factor to the perimeter of the original triangle.

• Multiply the perimeter of the original triangle by the scale factor.

• Subtract the scale factor from the perimeter of the original triangle.

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CCSS.HSG.SRT.B.4

If you are 6 feet tall and cast a shadow 4 feet long, and a tree casts a shadow 90 feet long, how tall is the tree?

• 150 feet

• 135 feet

• 165 feet

• 120 feet

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CCSS.HSG.SRT.A.2

What is the first step in solving a problem involving similar triangles and shadows?

• Draw a picture of the scenario.

• Measure the height of the tree.

• Find the perimeter of the triangle.

• Calculate the scale factor.

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CCSS.7.G.B.5

In the shadow problem, what assumption is made about the angles formed by the sun?

• The angles are obtuse.

• The angles are congruent for each object.

• The angles are different for each object.

• The angles are right angles.

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CCSS.HSG.SRT.A.2

What is the key concept to understand when working with similar triangles?

• The corresponding angles are different.

• The triangles must have the same perimeter.

• The corresponding sides are proportional.

• The triangles must have the same size.

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CCSS.HSG.SRT.A.2