The equation x² + 81 = (x + 10)² is equivalent to 
<h3>How to determine the equivalent equation?</h3>
The equation is given as:

Square both sides
x² + 81 = (x + 10)²
Although it can be further simplified, the above equation is equivalent to 
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Answer:
A. Cos θ = 16/42
Step-by-step explanation:
The angle the ladder makes with the floor = θ
Hypotenuse = length of the ladder = 42 m
Adjacent = Distance from the bottom of the ladder to the wall = 16 m
Therefore to find θ, we would apply the trigonometric function, CAH:
Cos θ = adj/hyp
Which is:
Cos θ = 16/42
The answer to the question is c