Special Right Triangles – Investigation Worksheet

Let students discover the side-length patterns in 45–45–90 and 30–60–90 triangles. Guided problems connect the Pythagorean theorem to shortcuts they can use in later geometry work.
Grades
Grade 8, High School
File type
Microsoft Word
Answer key
Included

Updated Sep 19, 2021

Subject
Math, Geometry
Topic
Special right triangles, 45-45-90 triangles
Resource types
Worksheets
Answer key
Included
Standards
8.G.B.7

Product description

From the author

This study guide comes with an answer key!

In the classroom

Teaching tips & learning objectives

Learning objectives

  • Use the Pythagorean theorem to find side lengths in 45–45–90 triangles
  • Derive and apply the side-length shortcuts for both special-triangle types
  • Bisect an equilateral triangle and label the resulting 30–60–90 triangle

Teaching tips

  • Complete the perfect-squares and radical-simplification warm-up before the triangle problems.
  • Let students investigate several triangles before revealing the shortcut.
  • Use the printed summary boxes to check the patterns students discover.

Skills covered

  • Pythagorean theorem — students calculate unknown sides of isosceles right triangles.
  • Radical simplification — students simplify square roots used in side-length calculations.
  • Pattern discovery — students derive special-triangle shortcuts from repeated calculations.

Good to know

Questions teachers ask about this resource

What should students review before starting the investigation?

Review perfect squares, simplifying radicals, and the Pythagorean theorem. The worksheet begins with related warm-ups before students investigate the special-triangle patterns.

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Curriculum

Standards, concepts & topics

Standards

  • 8.G.B.7 — Practices finding unknown right-triangle side lengths with the Pythagorean theorem.

Core concepts

  • Pythagorean Theorem

  • Special right triangles

  • 45-45-90 triangle

  • 30-60-90 triangle

  • Radical simplification

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