Triangulation and Survey Points

Introduction

Before GPS technology, surveyors relied on triangulation points (trig points) - permanent concrete markers placed at surveyed locations across the landscape. By measuring angles from these known positions, surveyors could calculate distances to far-off landmarks, determine heights of mountains, and create accurate maps. The technique uses the principles of triangles: if you know one side and two angles, you can calculate all other dimensions. This exploration examines how triangulation works, why it's still important today, and how it connects to modern surveying techniques. Pick a real structure you can see from two points a known distance apart - a school building, a church tower, a hill - and use it as your target throughout.

Guiding Questions

• From two points a known distance apart, you measure angles to a landmark. How does that fix its position?
• Carry out a real triangulation using your phone's clinometer app to find the height of a building or tall structure you can see from two points a measured distance apart. How accurate is your result?
• Use the sine rule to propagate your measurements, then check by direct measurement where possible.
• How does the shape of your triangle affect the accuracy? Find the best baseline for a given target.