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## Class 11 Physics (India)

### Course: Class 11 Physics (India)>Unit 2

Lesson 1: Physical quantities and their measurement

# Parallax method

## Problem

While exploring some rocky cliffs, you notice a lighthouse in the distance that you can't quite reach. It would be nice to know how far away that lighthouse is, but there is no way to make a direct measurement over the uneven terrain. Luckily you have your trusty compass and some knowledge about parallax and triangles!
For the first vantage point, you start with the lighthouse directly north of you. You then pace out $120$ steps (about $100$ meters) west. From this new spot, you measure the angle between due north and the lighthouse as $12$ degrees.
Given that, determine the average distance to the lighthouse. (Round to $1$ decimal place.)
meters
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