pythagorean theorem

 

A 20-foot wire connects the top of a utility pole to a point on the ground located 10 feet away from the base of the pole. What is the height of the pole? (Round to the nearest tenth.)     

 

by Pythagoras' Theorem              a² + b²  =  c²     

therefore                                       b²  =  c² – a²     (b is the pole)

 

                                                     b²  =  20² – 10²     

                                                     b²  =  400 – 100     

                                                     b¹  =  sqrt(300)     

                                                     b¹  =  17.3     

 

Another way would be to use cosine to find the larger acute angle,      

and then use tangent to find the height of the pole.     

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