Obtuse Triangles: Find The Missing Base

When you begin the Obtuse Triangles: Find The Missing Base worksheet, you explore triangles with one angle greater than 90 degrees. Although these triangles look stretched or wide, their area still depends on the familiar triangle formula. However, instead of finding the area, you work backward to determine the missing base. This turns geometry into a fun detective-style challenge where you use clues, measurements, and mathematical reasoning to uncover hidden values.

This worksheet teaches you how to rearrange the triangle area formula:
Area = ½ × base × height
to solve for the base:
base = (2 × Area) ÷ height.
You learn how to identify the correct height of an obtuse triangle, which often lies outside the shape because of the extended altitude. Each example guides you step by step, showing how to substitute values and isolate the base. Soon, the idea of reversing formulas becomes something you can do confidently.

As you solve problems, your spatial reasoning and attention to detail grow stronger. Some triangles may look confusing at first, but the worksheet helps you analyze diagrams to locate the true height and use the area correctly. You learn that not every measurement on a drawing is useful—only the height perpendicular to the base matters. Each question challenges you to think carefully rather than guess, making your problem-solving skills sharper.