How to Find Missing Sides of Similar Triangles

The Organic Chemistry Tutor

This educational video provides a comprehensive tutorial on finding missing side lengths in similar triangles using proportions. The instructor systematically guides viewers through four distinct examples that increase in complexity, demonstrating how to identify corresponding sides based on congruent angles and how to set up algebraic equations to solve for unknown variables. The content covers key geometric concepts including triangle similarity, corresponding parts, and ratio/proportion. It progresses from basic right triangles with integer sides to more complex scenarios involving scalene triangles, algebraic expressions (binomials) as side lengths, and vertical angle configurations (hourglass figures). The video emphasizes the importance of using angle markings to correctly match sides rather than relying on visual orientation. For educators, this video serves as an excellent instructional tool for Geometry and Algebra students. It explicitly models the procedural thinking required to solve geometry problems, including setting up proportions, cross-multiplying, using the distributive property, and simplifying fractions to make mental math easier. The step-by-step approach makes it ideal for introducing the topic or reviewing for assessments.