Step-by-step explanation:
this creates a right-angled triangle with the flagpole and the shadow being the 2 legs, and the distance top of flagpole to the end of the shadow is the Hypotenuse.
per Pythagoras we have then
Hypotenuse² = 76² + 60² = 5776 + 3600 = 9376
Hypotenuse = 96.8297475... ft
now, per law of sine
a/sinA = b/sinB = c/sinC
with a, b, c being the sides of the triangle, A, B, C being the corresponding opposite angles,
we have
flagpole length/sin(bottom right angle = angle of elevation) = Hypotenuse / sin(90°).
sin(90°) = 1
so,
76/sin(angle of elevation) = 96.8297475.../1
sin(angle of elevation) = 76/96.8297475... =
= 0.784882766...
angle of elevation = 51.70983681...° ≈ 51.7°