This math topic focuses on geometric problem-solving, specifically calculating unknown angles in triangles positioned adjacent to flat lines, with external angles. It is aimed at practicing the fundamentals of angle measurements within 2D polygons. Each problem presents a triangle with unknown angle X, alongside multiple-choice answers. The skill level is introductory, providing a foundational understanding of 2D polygon geometry.

Work on practice problems directly here, or download the printable pdf worksheet to practice offline.