Answer:
0.86°
Step-by-step explanation:
The relations between trig functions and sides of a right triangle are summarized in the mnemonic SOH CAH TOA. It tells you the relation between an angle and its adjacent and opposite sides is ...
Tan = Opposite/Adjacent
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The geometry described in the problem statement is modeled by the right triangle shown in the attachment. (The horizontal scale has been compressed.) The angle of interest has an adjacent side of 400 ft. Its opposite side is the additional elevation the ball must have to clear the fence (8 ft - 2 ft) = 6 ft.
For angle α, we have the relation ...
tan(α) = (6 ft)/(400 ft) = 0.015
The inverse tangent function can be used to find the angle from its tangent:
α = arctan(0.015) ≈ 0.859372°
The angle of elevation needs to be a minimum of 0.86°.