What percentage of grade corresponds to a 45-degree angle?

Prepare for the A-5 Excavating, Grading and Oil Surfacing Test with flashcards and multiple choice questions. Succeed with detailed explanations and hints for each question. Ensure your success in the exam!

The correct answer is based on the relationship between the angle of inclination and the percentage of grade. A 45-degree angle corresponds to a rise equal to the run, meaning that for every unit of horizontal distance, there is an equal unit of vertical rise.

To convert an angle to a percentage grade, you can use the tangent function from trigonometry, which in the case of a 45-degree angle has a tangent value of 1. This indicates that the grade is 1:1, or 100 percent. In terms of practical terms, this means for every 1 foot of horizontal distance traveled, the elevation changes by 1 foot, leading directly to a 100 percent slope.

The other choices reflect different angles of slope that do not correspond to a 45-degree angle. For instance, a 50 percent grade corresponds to a much shallower angle, while a 75 percent grade would be steeper, but not as steep as represented by 100 percent. Therefore, the identification of a 45-degree angle specifically correlates directly with a 100 percent grade.

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