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Find the angular size of a circular object with a 4​-inch diameter viewed from a distance of 5 yards.

 Jul 11, 2019
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5 yards  =  180  in

 

We have a right triangle with a hypotenuse drawn from the vantage point to the center of the circle =  (2 in + 180 in)  =  182 in   and a leg of 2 in which meets a tangent drawn to the circle from the vantage point

 

We can use the arcsin function to  find  (1/2) of the measure of the angle  we need......so we  have

 

arcsin (2/182)  = θ  ≈  .63°

 

So....twice the measure of this angle is what we need  ≈ 1.26°

 

 

cool cool cool

 Jul 12, 2019

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