🔍 Key Concepts

• Boom angle indicators on cranes/derricks • Relationship between boom angle and horizontal vs. vertical reference lines • How boom angle affects radius and lifting capacity

💭 Think About

• When you measure an angle on a boom, what fixed reference line do you normally use in basic geometry and crane operations? • Think about how protractors measure angles: do they usually start from a horizontal baseline or a vertical one? • Which choice describes a simple, constant reference line that does NOT change when the load moves or swings?

✅ Before You Answer

• Make sure the reference is tied to the boom itself, not the load • Confirm that the reference line would stay constant, even if the load swings or changes height • Check whether the term describes an angle from a baseline, not two moving objects relative to each other