Answer: Approximately 49 degrees
A slightly more accurate angle value is about 49.458398 degrees.
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Step-by-step explanation:
Draw a right triangle as shown in the diagram below. The horizontal leg is 13 ft and the hypotenuse is 20 ft. The angle between these two sides is what we want to find.
With this reference angle, the adjacent side is 13 and the hypotenuse is 20. We use the cosine ratio to tie the sides together with this angle.
Let x be the unknown angle.
cos(angle) = adjacent/hypotenuse
cos(x) = 13/20
cos(x) = 0.65
x = arccos(0.65)
x = 49.4583981264954
x = 49
I'm rounding to the nearest whole number since the given values (13 and 20) are also whole numbers. If your teacher provides other rounding instructions, then be sure to follow that of course.
The angle of elevation is roughly 49 degrees. Make sure your calculator is in degree mode. The notation "arccos" stands for "arccosine" and it's the same as inverse sine.